As salamu alaykum. 

Ahlus Sunnah believe that when we call upon Prophets and Awliya for help then it is a form of Tawassul. And Asking directly is in Majaaz whereas real helper and doer is Allah alone. 

First of all Ahlus Sunnah accept and believe that Prophets and especially our Prophet (Peace be upon him) remain alive in their graves, hear us, intercede for us, and can be called upon. 

حدثنا أبو الجهم الأزرق بن علي حدثنا يحيى بن أبي بكير حدثنا المستلم بن سعيد عن الحجاج عن ثابت البناني عن أنس بن مالك : قال رسول الله صلى الله عليه و سلم: الأنبياء أحياء في قبورهم يصلون

 إسناده صحيح 

Translation: On the authority of Anas (RA) the Prophet (Peace be upon him) said: The Prophets are alive in their graves and praying [Musnad Abu Ya’la with Sahih Chain, Volume No.6, Page No. 147, Hadith No. 3425. Even Salafi authority Albani accepted it to be Sahih] 

Regarding the hadith in Sahih Muslim that our Prophet a.s saw Musa a.s praying in his grave. Regarding it Imam al Manawi (rah) quoted Imam al Qurtubi (rah) saying. 

الحديث بظاهره يدل على أنه رآه رؤية حقيقية في اليقظة وأنه حي في قبره يصلي الصلاة التي يصليها في الحياة وذلك وذلك ممكن ولا مانع من ذلك

Translation: This hadith apparently proves that sight of Prophet (Peace be upon him) was REAL and in state of awakening. And he (Musa a.s) is “ALIVE IN GRAVE AND PRAYING, LIKE THE ALIVE PRAY” this is possible and there is no objection to it [Faydh ul Qadeer (5/663)] 

Qur'an states: 

وَلَا تَقُولُوا لِمَن يُقْتَلُ فِي سَبِيلِ اللَّهِ أَمْوَاتٌ ۚ بَلْ أَحْيَاءٌ وَلَٰكِن لَّا تَشْعُرُونَ

Translation: And do not say about those who are killed in the way of Allah ,"They are dead." Rather, they are alive, but you perceive [it] not. [The Glorious Qur’an 2:154]

In another verse it states: 

وَ لَا تَحۡسَبَنَّ الَّذِیۡنَ قُتِلُوۡا فِیۡ سَبِیۡلِ اللّٰہِ اَمۡوَاتًا ؕ بَلۡ اَحۡیَآءٌ عِنۡدَ رَبِّہِمۡ یُرۡزَقُوۡنَ 

And "NEVER THINK" of those who have been killed in the cause of Allah as dead. Rather, they are alive with their Lord, receiving provision. 

Qur'an, 3:169

Wahabis create doubt over last 2 words of first Ayah i.e. لَّا تَشْعُرُونَ  so it is necessary to explain the Hayaat of Anbiya/Shuhada/Saliheen. Logically speaking we do not see Angels but does that mean they are not alive or present? Hence if we do not have Sha’oor of something then it does not mean it is negated. From many hadiths and explanations of Prophet (Peace be upon him) we do get to know about the magnificent and definitive life especially that of Prophets in their graves and they being linked to Duniya as you will know from my this post if you read completely. 

The Prophet (ﷺ) said: If "ANY ONE"  of you greets me, Allah returns my soul to me and I respond to the greeting. [Sunnan Abu Dawud, Book 10, Hadith 2036. The hadith  is decalred “Hasan (good)” even by Albani]

Even though Imam Abu Dawud (rah) has mentioned it in chapter of Visiting graves. However still the hadith remains Mutlaq because Prophet (Peace be upon him) did not restrict it to his grave only. Plus even if it refers to grave only then still it proves our point that Prophet can hear multiple salams and other talks (this will be proven ahead) 

Narrated Anas bin Malik: Allah's Messenger (ﷺ) said, "When (Allah's) slave is put in his grave and his companions return " HE EVEN HEARS THEIR FOOTSTEPS", two angels come to him and make him sit and ask, 'What did you use to say about this man (i.e. Muhammad)?' The faithful Believer will say, 'I testify that he is Allah's slave and His Apostle… [Sahih Bukhari: 2.23.456]

This is the situation of ordinary Muslim then what status of our Prophet be ..Subhan Allah. Hence proven that Prophets and Awliya hear us in their graves. Read Ibn Qayyim al Jawziyyah's magnificent book "Kitab ar Ruh" for more details on Sima al Mawta. 

Book 024, Number 5149: (Sahih Muslim)

…Narrated by Sayyidah Asma bint Abi Bakr (RA). Whereupon she said: Here is the cloak of Allah's Messenger (may peace be upon him). and she brought out to me that cloak made of Persian cloth with a hem of brocade, and its sleeves bordered with brocade and said: This was Allah's Messenger's cloak with 'A'isha until she died, and when she died. I got possession of it. The Apostle of Allah (may peace be upon him) used to wear that, and "WE WASHED IT FOR THE SICK AND SOUGHT CURE THEREBY"

May our parents be taken ransom for great Sahaba who even took the blessed cloak of the Prophet (Peace be upon him) as a means to cure, and we can only have pity upon those people who deny intercession through the blessed Dhaat (personality) of the Prophet (Peace be upon him).

Qur'an states: 

اِذۡہَبُوۡا بِقَمِیۡصِیۡ ہٰذَا فَاَلۡقُوۡہُ عَلٰی وَجۡہِ اَبِیۡ یَاۡتِ بَصِیۡرًا ۚ وَ اۡتُوۡنِیۡ بِاَہۡلِکُمۡ  اَجۡمَعِیۡنَ

(Yusuf Peace be upon him said): Take this, my shirt, and cast it over the face of my father; HE WILL BECOME SEEING. And bring me your family, all together." 

Surah Yusuf, Verse 93. 

When a shirt of a Prophet can cure eyesight, due to being blessed of being worn by a Prophet. Then why cannot the greatest Prophet Muhammad (Peace be upon him) who is Rahmat al lil Alameen, and other Saliheen be called upon to seek cure in Majazi sense i.e. by believing real helper is Allah alone. Plus Where does the verse in Surah Yusuf ,93 say that Ask Allah along and only then my shirt will cure?

If someone says this is not linked to Istighatha (although It sure is) then opponents should accept that all the verses from Quran which they misuse to disapprove Istighatha from Prophets and Awliya then according to those verses we cannot even seek cure from left overs of Anbiya either. Hence proven those verses are for idols and disbelievers whereas Shariah approves taking Tabbaruk and Shifa from Anbiya, and nowhere Shariah allows to seek blessings from idols or disbelievers. 

The Mutlaq hadith of Uthman bin Hunaif RA states: 

عن ‏ ‏عثمان بن حنيف

أن رجلا ضرير البصر أتى النبي ‏ ‏صلى الله عليه وسلم ‏ ‏فقال ادع الله لي أن يعافيني فقال إن شئت أخرت لك وهو خير وإن شئت دعوت فقال ‏ ‏ادعه ‏ ‏فأمره أن يتوضأ فيحسن وضوءه ويصلي ركعتين ويدعو بهذا الدعاء اللهم إني أسألك وأتوجه إليك ‏ ‏بمحمد ‏ ‏نبي الرحمة يا ‏ ‏محمد ‏ ‏إني قد توجهت بك إلى ربي في حاجتي هذه ‏ ‏لتقضى اللهم شفعه في

 It was narrated from 'Uthman bin Hunaif that a blind man came to the Prophet (Peace be upon him) and said: "Pray to Allah to heal me." He said: "If you wish to store your reward for the Hereafter, that is better, or if you wish, I will supplicate for you." He said: "Supplicate." So he told him to perform ablution and do it well, to pray two Rak'ah, and to say this supplication: O Allah, I ask of You and I turn my face towards You by the intercession of Muhammad the Prophet of mercy (Peace be upon him). O Muhammad (Peace be upon you), I have turned to my Lord by your intercession concerning this need of mine so that it may be met. O Allah, accept his intercession concerning me.

References:

►Ibn Majah transmitted it in his Sunan, book of Iqamat al-salat wa al-sunnat (establishing prayer and its sunnahs) [Hadith No#1385. Declared Sahih by Salafi Dar us Salam publication] 

►Tirmidhi in al-Jami’ Book of da‘awat (supplication) Vol. 6, Book 46, Hadith 3578, where Imam at-Tirmidhi declared it "HASAN SAHIH GHARIB" and also declared Sahih by Dar us Salam publication. 

This hadith is Mutlaq so we can seek intercession of our Prophet and also call him directly. 

Salafis falsely say that this Hadith only refers to physical life of Prophet (Peace be upon him). This is their false interpretation. Let me first quote a big Salafi authority Qadhi Shawkani that this hadith is Mutlaq and still applicable. 

قوله ويتوسل إلى الله سبحانه بأنبيائه والصالحين أقول ومن التوسل بالأنبياء ما أخرجه الترمذي وقال حسن صحيح غريب والنسائي وابن ماجة وابن خزيمة في صحيحه والحاكم وقال صحيح على شرط البخاري ومسلم من حديث عثمان بن حنيف رضي الله عنه أن أعمى أتى النبي صلى الله عليه وسلم فقال يا رسول الله ادع الله أن يكشف لي عن بصري قال أو أدعك فقال يا رسول الله أني قد شق علي ذهاب بصري قال فانطلق فتوضأ فصل ركعتين ثم قل اللهم أني أسألك وأتوجه إليك بمحمد نبي الرحمة الحديث وسيأتي هذا الحديث في هذا الكتاب عند ذكر صلاة الحاجة وأما التوسل بالصالحين فمنه ما ثبت في الصحيح أن الصحابة استسقوا بالعباس رضي الله عنه عم رسول الله صلى الله عليه وسلم وقال عمر رضي الله عنه اللهم إنا نتوسل إليك بعم نبينا

Translation: Qadhi Shawkani explains the saying of Imam Ibn al-Jarzi (rah) i.e. One (should) ask Allah through the intermediary of Prophets and Pious servants of Allah: I (Qadhi Shawkani) say that to seek Intercession with Allah through Prophets and Righteous (is proven) as is narrated by Tirmidhi who called it Hassan Sahih Gharib, also narrated by Nasa’i, Ibn Majah, Ibn Khuzayma in his “Sahih” Hakim who said: It is Sahih on the criteria of Bukhari and Muslim, the Hadith of Uthman bin HUNAIF (ra) that a blind man came to the Prophet (Allah bless him & give him peace) and said: “I've been afflicted in my eyesight, so pray to Allah for me". The Prophet (Allah bless him & give him peace) said: “Go perform ablution (Wudu), perform two rak'at Salat and then say: “O Allah!I ask you and turn to you through my Prophet Muhammad. This hadith is mentioned in the book (with chapter) of Salaat al Hajah. And regarding Tawassul through righteous people, It is proven from Sahih (Bukhari) that Sahaba used to seek rain through Abbas (ra) the uncle of Prophet (Peace be upon him). Umar (ra) said: O Allah we turn to you through the means of Prophet's uncle [Tuhfa tul Dhakireen, Page No. 48]

Nawab Saddiq Hasan Khan Bhopali is considered as the top notch Wahabi scholar of Sub continent. His works are even published in Saudi Arabia with Tahqeeq. His work Nuzul Abrar is famous in Arab world too. He says in this book:

Translation: [In Explaining Imam Ibn al Jazri – Rahimahullah’s qawl that One (should) seek intercession of Prophets to Allah, Nawab Sadiq Hassan Khan Bhopali the leading Wahabi authority says]: 

The Tawassul towards Allah Subhanahu wa Ta’ala through Prophets, the “PROOF” on this is as narrated in Tirmidhi the hadith of Uthman bin Hunayf that a blind man came to the Prophet (Peace be upon him) and said (Then Bhopali quotes the hadith which has already been shown above) 

(Bhopali said): And in regards to Tawassul through Saliheen (righteous) then Daleel on this is as proven from Sahih that Sahaba did Istisqa through al-Abbas (RA) the uncle of Prophet (Peace be upon him). Umar (RA) said: O Allah we (now) seek intercession with you by the uncle of our Prophet. 

(Bhopali now refutes Wahabism and said): This matter of Tawassul through Prophets and Saliheen was disputed by people of knowledge in such a strict (shadid) manner that it reached to an extent where “SOME STARTED TO DO TAQFIR ON SOME OTHER OR CALLED EACH OTHER AS INNOVATORS OR MISGUIDED” although this matter was not that complicated nor was there any such need of such (disputation). The author of Book called “Ad-deen al Khalis” and Allama Shawkani in his “Dur an-Nadheed fi Ikhlaas at-Tawhid” have completed the research in this regard, the “SUMMARY” of which is that Tawassul is allowed through them (Prophets and Saliheen) and according to some narrations Qasr (restriction to Prophet) should be done and nobody else should be done Qiyaas on this, nor anything be added. We have “NO DOUBT” that anyone who does not consider Tawaassul to be “KHAAS WITH ALLAH” has “NO BLAME ON HIM” and whosoever considers opposite to this is also not to be blamed because he did something permitted. Similarly Tawassul could be taken through good deeds as we pointed towards it before. In summary this matter is “NOT SUCH THAT IT IS MATTER OF TAZALZUL (TO BASH EACH OTHER)” but there is (no cure) for ignorance, Ta’sub (hatred) and Taqleed (of wrong viewpoints) and they are too many to mention. [Nuzul Abrar, Page # 37-38 in Dar ul Ma’rifah edition and Page # 75-76 in Dar Ibn Hazm edition]

Hence proven that the hadith of Uthman bin Hunaif having words of directly calling Prophet (Peace be upon him) from near or far and seeking his intercession is absolutly fine. 

Plus there is also an authentic Athar from same Uthman bin Hunaif (RA) after the Zahiri passing away of Prophet (Peace be upon him) when a man came for his need to meet Uthman bin Affan (RA) but he did not attend him first, so he was taught the supplication of taking Waseela of Prophet and also of calling him directly. This Athar is also declared Sahih by authorities of Ahlus Sunnah. 

See Mu’jam as-Sagheer 1/306-307, Hadith # 508. Dalayl un Nubuwah (6/168), Published by Dar ul Kutb al ILmiyyah, and others. 

Imam Ibn Yusuf al-Salhi (rah) said: 

الباب الخامس في ذكر من توسل به - صلى الله عليه وسلم - بعد موته

روى الطبراني والبيهقي - بإسناد متصل ورجاله ثقات - عن عثمان بن حنيف أن رجلا كان يختلف إلى عثمان بن عفان في حاجة

Translation: Chapter 5: Regarding Tawassul through the Prophet (Peace be upon him) "AFTER HIS DEATH". It is narrated by At-Tabrani and al-Bayhaqi "WITH CONTINEOUS CHAIN (بإسناد متصل) HAVING THIQA NARRATORS" the hadith of Uthman bin Hunaif (ra) that a man came to Uthman bin Affan (ra) regarding his Hajah .. until the end of same hadith [Muhammad bin Yusuf al-Salihi in Subl ul Huda War Rashaad, Volume No.12, Page No. 407]

Salafis cannot quote a single mutually agreed upon scholar who called this Athar as weak. 

حدّثنا أبو معٰوية عن الأعمش عن أبي صالح عن مٰلك الدار ، قال: وكان خازن عمر على الطعام، قال: أصاب الناس قحط في زمن عمر، فجاء رجل إلى قبر النبي صلى الله عليه وسلم فقال : يا رسول الله استسق لأمتك فإنهم قد هلكوا، فأُتِيَ الرجل في المنام فقيل له: ائت عمر فأقرئه السلام، وأخبره أنكم مستقيمون وقل له: عليك الكيس عليك الكيس فأتى عمر فأخبره فبكى عمر ثم قال: يا رب لا آلو إلاّ ما عجزت عنه

قال حافظ ابن كثير : وهذا اسناد صحيح

Malik ad-Dar i.e. treasurer of Umar (RA) relates: The people were gripped by famine during the tenure of Umar (Ibn-ul-Khattab RA). Then a man walked up to the grave of the Prophet and said: O Messenger of Allah! Ask for rain from Allah for your Ummah who is in dire straits. Then he saw the Prophet (SAW) in a dream. The Prophet (SAW) said to him, Go over to Umar, give him my regards and tell him that the rain will come to you. And tell Umar that he should be on his toes, he should be on his toes (he should remain alert). He went over to see Umar and passed on to him the tidings. On hearing this, Umar broke into a spurt of crying. He said, O Allah, I exert myself to the fullest until I am completely exhausted.

References:

Al-Musannaf Ibn Abi Shaybah Volume 011, Page No. 118, Hadith Number 32538 

Its chain is declared Sahih by:

Imam Ibn Kathir (rah) in Al Bidayah Wan Nihayah Volume No. 5, Page No. 167

Imam Ibn Hajr al-Asqalani (rah) in Fath ul Bari : Volume No.2, Page No. 495

Imam Qastallani in al-Mawahib-ul-laduniyyah (4:276)

And others. 

Shaykh ul Islam Imam Taqi ud din as Subki (rah) has done Istadlal from it in his book "Shifa us Siqaam" to prove Waseela and Istighatha from Prophet (Peace be upon him) 

The Sahih and Mashoor (famous) report of Umar (RA) calling Sariyah (RA) from far and helping him (Note: Sariyah also heard the call).

عن ابن عمر قال: وجه عمر جيشا وأمر عليهم رجلا يدعى سارية فبينما عمر يخطب يوما جعل ينادي: يا سارية الجبل - ثلاثا، ثم قدم رسول الجيش فسأله عمر، فقال: يا أمير المؤمنين! لقينا عدونا فهزمنا، فبينا نحن كذلك إذ سمعنا صوتا ينادي: يا سارية الجبل - ثلاثا، فأسندنا ظهورنا إلى الجبل فهزمهم الله، فقيل لعمر: إنك كنت تصيح بذلك. 

(ابن الأعرابي في كرامات الأولياء والديرعاقولي في فوائده وأبو عبد الرحمن السلمي في الأربعين وأبو نعيم عق معا في الدلائل واللالكائي في السنة، كر، قال الحافظ ابن حجر في الإصابة: إسناده حسن).

Translation: Ibn Umar (RA) narrates that Umar ibn ul Khattab (RA) once deputed an army and made a person Ameer upon them who was called Sariyah (RA). After this one day when Umar (RA) was giving sermon, he called out (loudly): Ya Sariyah, the mountain, and he proclaimed this thrice (يا سارية الجبل - ثلاثا ). When the messenger of that army came and asked Umar (RA), by saying: O Ameer ul Mo'mineen! We confronted the enemy and we were getting defeated, but "SUDDENLY A VOICE WAS HEARD" i.e. O Sariyah, the mountain, and this was heard thrice. We turned our backs towards the mountain and due to this Allah defeated the enemy. He asked Umar (RA) were you proclaiming that?

Imam al-Hindi gives references via Imam Ibn Hajr al-Asqalani (rah)'s al-Isaba and quotes Ibn Hajr saying: 

قال الحافظ ابن حجر في الإصابة: إسناده حسن 

Translation: al-Hafidh Ibn Hajr said in al-Isaba: The Chain is "HASAN" [Kanz ul Amaal, Hadith # 35788, or see Urdu version, Volume # 12, Page # 608, Published by Dar ul Ishaat, Urdu Bazaar, Lahore, Pakistan. Also see Isaba fi Tamiyz as Sahaba by Ibn Hajr al Asqalani, Volume # 3, Page # 4, under biography of Sariyah bin Zaneem RA]

Imam Shams ud din al Ramli (rah) in his Fatwa of permitting Istighatha has cited this proof as well. I have already shown Imam al Ramli (rah)'s Fatwa in other comment. 

If someone says that Sayyiduna Sariyah (ra) did not call Sayyiduna Umar r.a himself for help so this daleel cannot work. Then the answer is that Sayyiduna Umar r.a being a Wali can see and know from far and can help ma fawq al asbab, then asking him for help is بطریق اولی  justified. If someone says It was Karamah then no problem because we also believe Prophets and Awliya helping us is their Miracle and Karamah, and Allah makes them hear. 

قال رسول الله ‏ ‏صلى الله عليه وسلم ‏ ‏إن الله قال ‏ ‏من عادى لي وليا فقد ‏ ‏آذنته ‏ ‏بالحرب وما تقرب إلي عبدي بشيء أحب إلي مما افترضت عليه وما يزال عبدي يتقرب إلي بالنوافل حتى أحبه فإذا أحببته كنت سمعه الذي يسمع به وبصره الذي يبصر به ويده التي يبطش بها ورجله التي يمشي بها وإن سألني لأعطينه ولئن استعاذني لأعيذنه وما ترددت عن شيء أنا فاعله ترددي عن نفس المؤمن يكره الموت وأنا أكره مساءته

Volume 8, Book 76, Number 509: (Sahih Bukhari – Hadith al Qudsi)

Allah’s Apostle said, “Allah said, “I WILL DECLARE WAR AGAINST HIM WHO SHOWS HOSTILITY TO A PIOUS WORSHIPPER OF MINE (I.E. WALI ULLAH)” And the most beloved things with which My slave comes nearer to Me, is what I have enjoined upon him; and My slave keeps on coming closer to Me through performing Nawafil (praying or doing extra deeds besides what is obligatory) till I love him, “SO I BECOME HIS SENSE OF HEARING WITH WHICH HE HEARS, AND HIS SENSE OF SIGHT WITH WHICH HE SEES, AND HIS HAND WITH WHICH HE GRIPS” and his leg with which he walks; "AND IF HE ASKS ME, I WILL GIVE HIM"  and if he asks My protection (Refuge), I will protect him; (i.e. give him My Refuge) and I do not hesitate to do anything as I hesitate to take the soul of the believer, for he hates death, and I hate to disappoint him.”

In explanation of this hadith I will cite 3 mighty scholars

Imam Fakhr ud din al-Razi (rah) who said:

وكذلك العبد إذا واظب على الطاعات بلغ إلى المقام الذي يقول الله كنت له سمعا وبصرا فإذا صار نور جلال الله سمعا له سمع القريب والبعيد وإذا صار ذلك النور بصرا له رأى القريب والبعيد وإذا صار ذلك النور يدا له قدر على التصرف في الصعب والسهل والبعيد والقريب.

Translation: When a person becomes totally dedicated to obedience (of Allah), then he becomes established on such a state about which Allah has said: I become his hearing and sight, hence when Allah’s Nur (light) becomes his hearing, “THEN HE HEARS FROM NEAR AND DISTANT PLACES”, and when Allah’s Nur becomes his sight then he sees from near and distant places and when Allah’s Nur becomes his hand then “HE CAN MAKE TASSARUF (I.E. HELP/BRING CHANGE)” in difficult and easy problems “FROM NEAR AND FAR” [Tafsir ul Kabir, Volume No. 21, Page No. 77]

Imam Fakhr ud din ar-Razi (rah) also said:

الأنبياء، وهم الذين أعطاهم الله تعالى من العلوم والمعارف ما لأجله بها يقدرون على التصرف في بواطن الخلق وأرواحهم، وأيضا أعطاهم من القدرة والمكنة ما لأجله

يقدرون على التصرف في ظواهر الخلق

Translation: The Prophets are granted with so much knowledge and Marifah (deep understanding) by Allah that they have the power “TO DO TASSARUF IN BATIN OF CREATION AND THEIR SOULS… AND APPARENT OF CREATION” [Tafsir ul Kabir, Volume No. 7, Under 6:88]

Mullah Ali Qari (rah) states in his magnificent Mirqaat Sharh al Mishkaat

والمواظبة على العلم والعمل وفيضان الأنوار الإلهية حتى يقوى النور وينبسط في فضاء قلبه فتنعكس فيه النقوش المرتسمة في اللوح المحفوظ ويطلع على المغيبات ويتصرف في أجسام العالم السفلي بل يتجلى حينئذ الفياض الأقدس بمعرفته التي هي أشرف العطايا

Translation: Due to knowledge, implementation, and Faydh of Allah’s benevolence, the Nur becomes strong and spreads in every corner of the heart, then it starts to see the images of preserved tablet, then it knows about the Unseen matters “AND ALSO STARTS TO DO TASSARUF (HELP/BRING CHANGE) IN LOWER WORLD” rather the Faydh of the Lord with His Marifah manifests on it, which is the best of all grants [Mirqaat, Sharh al Mishkaat, Volume No. 1, Page No. 26]

Allama Anwar Shah Kashmiri, the famous Deobandi commentator and scholar clarifies the confusion that some people try to create over this hadith, he writes (rough translation):

That which (some) scholars of sacred law have said that the bodily parts of slave become obedient to will of Allah to the extent that they do not do anything other than what Allah demands, so it would be correct to say that he does not listen except for Allah, he does not speak except for Allah. “I SAY THESE WORDS DO NOT DO JUSTICE TO THE ACTUAL WORDING OF HADITH” because “KUNTU SAMAHU” with the Seegha Mutakalim proves that a person getting closeness of Allah through prayers and nawafil only becomes a Skeleton and body "AND THE MUTASARRAF BECOMES THE DIVINE PRESENCE ONLY", which is what the Sufis meant by annihilation in Allah. That is, detachment from his naf's motives so that none is left to be mutasarraf but Him (Allah) and in the hadith is a glimpse of Wahadat ul-Wujood and our Mashaikh were fond of this issue (وحدة الوجود) until the times of Shah Abdul Aziz but as far as I am concerned, I am not strict about it [Faydh al Bari Sharh Sahih al Bukhari, Volume No. 6 Page No. 270-271]

‏"‏إن لله ملائكة في الأرض سوى الحفظة يكتبون ما يسقط من ورق الشجر، فإذا أصاب أحدكم عرجة بأرض فلاة فليناد‏:‏ أعينوا عباد الله‏"‏‏.‏ 

رواه البزار ورجاله ثقات‏.‏

Translation: Allah has angels on the earth - other than the [two] record-keepers - who keep a record [even] of the leaves that fall on the ground. Therefore, if one of you is crippled in a deserted land where no-one is in sight, let him cry out: " HELP O ALLAH'S SERVANTS"

Imam al Haythami (rah) said after this hadith: It is narrated by Al-Bazzar and all its narrators are reliable (thiqa) [Reference: Majma uz Zawaid, Volume 10, Hadith No. 17104]

This hadith is not only authentic but rather it has been “ACTED UPON” by great scholars

إِذَا أَضَلَّ أَحَدُكُمْ شَيْئًا أَوْ أَرَادَ أَحَدُكُمْ عَوْنًا وَهُوَ بِأَرْضٍ لَيْسَ بِهَا أَنِيسٌ، فَلْيَقُلْ:"يَا عِبَادَ اللَّهِ أَغِيثُونِي، يَا عِبَادَ اللَّهِ أَغِيثُونِي، فَإِنَّ لِلَّهِ عِبَادًا لا نَرَاهُمْ"، وَقَدْ جَرَّبَ ذَلِكَ

After Imam At-Tabarani transmitted the hadith of calling out : O Servants of Allah, Help me! In his Mu'jam al Kabir (17/117) he said “this has been acted upon (وَقَدْ جَرَّبَ ذَلِكَ)” Plus the narration in Mu'jam al Kabeer does not talk about Angels. 

The amal of great Imam of Salaf, Imam Ahmad bin Hanbal (rah). 

عبد الله بن أحمد بن حنبل قال سمعت أبي يقول حججت خمس حجج اثنتين راكب وثلاث ماشي أو ثلاث راكب واثنتين ماشي فضللت الطريق في حجة وكنت ماشيا فجعلت أقول يا عباد الله دلوني على الطريق قال فلم أزل أقول ذلك حتى وقفت على الطريق أو كما قال أبي

Translation: Abdullah bin Ahmed bin Hanbal (rah) said that he heard his father (Imam Ahmed) who said: I performed Hajj 5 times, thrice on foot and twice on ride or he said thrice on ride and twice on foot, once when I was on foot I lost my way hence I started to exclaim this: O Allah’s servants show me the way (يا عباد الله دلوني على الطريق), I kept on repeating this until I came back on track. [Imam Baihaqi in Shu’ab ul Iman, Volume 6, Page No 128,Narration No. 7697]

So Alhamdulillah the great Hadith specialists themselves acted upon it and approved it, had there been a hint of shirk in this then they would have mentioned it!

Imam Mullah Ali Qari (rah) in Sharh of Hisn-ul-Hiseen writes that our Prophet (Peace be upon him) said that: 

اذا انفلتت دابة احد كم بارض فلاة فليناد يا عباد الله احبسوا

Translation: If the animal of someone runs loose in jungle, then he should say: O Allah’s servants stop it (for full hadith see:Musnad Abu Ya'la # 5269. It also does not include wording Angels)

He writes under “Ibaad Allah”

المراد بهم الملىكة او المسلمون من الجن او رجال الغيب المستمون بابدال

Translation: It means the angels, Muslims, jinn or men of unseen i.e. Abdaal 

Then he writes: 

هذا حديث حسن يحتاج اليه المسافرون وانه مجرب

Translation: This hadith is Hasan (good) and the travelers are in urgent need of it and this has been acted upon [Sharh Hisn al Hiseen, Al-Hirz al-Thamin, page 378]

Even if Salafis restrict it to Angels only then according to Islamqa Salafi website asking Angels for help is Shirk al Akbar too ...Naudhobillah

Read this fatwa

Hence proven that asking Ghayr Ullah for help i.e. Anbiya, Awliya, Angels, and Jinns is allowed. 

Proof # 10 (Saying Ya Muhammadah to seek help) 

In narration of Adab al Mufrad of Imam Bukhari (rah) and in other books it says: 

حَدَّثَنَا أَبُو نُعَيْمٍ، قَالَ‏:‏ حَدَّثَنَا سُفْيَانُ، عَنْ أَبِي إِسْحَاقَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ سَعْدٍ قَالَ‏:‏ خَدِرَتْ رِجْلُ ابْنِ عُمَرَ، فَقَالَ لَهُ رَجُلٌ‏:‏ اذْكُرْ أَحَبَّ النَّاسِ إِلَيْكَ، فَقَالَ‏:‏ يَا مُحَمَّدُ

Abdur-Rahman ibn Sa'd said, Ibn 'Umar (RA)'s foot became numb. A man said to him, 'Mention the person you love most.' He said, "'YA Muhammad.'"

Adab al Mufrad # 964 (Wrongly declared weak by Albani and other Wahabis. This hadith is accepted to be Sahih by Ahlus Sunnah and it has turaq with Shu'ba (rah) narrating hence blame of Tadlees on Abi Ishaaq (rah) is lifted because according to Usool when Imam Shu'ba narrates then next narrators do not do Tadlees). 

Regarding this hadith Mullah Ali Qari (rah) said: 

أي فنادى بأعلى صوته (يا محمّداه) بسكون الهاء للندبة وكأنه رضي الله تعالى عنه قصد به اظهار المحبة في ضمن الاستغاثة

Meaning: He called him by raising his voice saying (Ya Muhammadah) with the Sukoon of Al-Ha in the form of Nudba (i.e. to call in pain). The intention of Ibn Umar r.a was his demonstration of love (And It was) IN CATEGORY OF ISTIGHATHA (SEEKING HELP FROM PROPHET PEACE BE UPON HIM) 

Mullah Ali Qari in Sharh Ash Shifa. Volume 2, pg. 43

Hence proven from Salaf and first three generations that Sahaba did Istighatha and took waseela of especially Prophet (Peace be upon him). 

In Mishkaat ul Masabih It states: 

سل فقلت أسألك مرافقتك في الجنة . قال أو غير ذلك ؟ . قلت هو ذاك . قال فأعني على نفسك بكثرة السجود . رواه مسلم

Translation: The Prophet (Peace be upon him) said to Ka'b (RA): Ask for something (O Ka'b). Ka'b said: I ask for your companionship in Jannah. The Prophet said: Do you want something else? He replied: Just this, the Prophet then said: help me by doing more prostrations – Taken from (Sahih) Muslim [Mishkat ul Misabih, Volume No. 1 Page No. 156] 

This hadith proves that the Sahabi asked for paradise from Prophet and the Prophet in return told him to ask for more. The Prophet did not say that you asked for Jannah from Ghair Ullah, hence you have become Mushrik!

Shaykh Abdul Haqq Muhadith Dhelvi (rah) who was and is accepted to be a great scholar by Salafis. He writes under this hadith:

The meaning of Prophet (Peace be upon him) saying “ASK” and not restricting it to something specific proves that all things are in hands of Prophet (Peace be upon him) and he can grant anyone whatsoever he wishes through the grant of Allah, because the world and hereafter are his Sikhawat (generosity) and the knowledge of Loh and Qalam  is part of his knowledge, If you are in need of anything relating to world or hereafter then come to the Prophet (Peace be upon him) and get your need fulfilled. [Ash’at ul Lamaat, Sharh al Mishqaat, Volume No.2, Page No. 247]

Mullah Ali Qari (rah) says:

يؤخذ من إطلاقه عليه السلام الأمر بالسؤال أن الله تعالى مكنه من إعطاء كل ما أراد من خزائن الحق

Translation: The Prophet (Peace be upon him) saying to “ASK” refers to Allah giving him capability to grant anything from the “TREASURES OF ALLAH” [Mirqat Sharh al Mishqaat (2/615)]

He also said:

وذكر ابن سبع في خصائصه وغيره إن الله تعالى أقطعه أرض الجنة يعطي منها ما شاء لمن شاء

Translation:  And Imam Ibn Saba' in his Khasais and others mentioned that Allah has given the land of Jannah to Prophet from which he gives to whoever he wants [Mirqaat Sharh al Mishqaat (2/615)]

Allah's Apostle said, "Name yourselves after me (by my name) but do not call (yourselves) by my Kuniya, for I am Al-Qasim (distributor), and I distribute among you Allah's blessings." This narration has also come on the authority of Anas that the Prophet said so."[Volume 8, Book 73, Number 216: (Sahih Bukhari). Wahabi translator Muhsin Khan]

Volume 2, Book 24, Number 553: (Sahih Bukhari)

The Prophet said, "A man keeps on asking others for something till he comes on the Day of Resurrection without any piece of flesh on his face." The Prophet added, "On the Day of Resurrection, the Sun will come near (to, the people) to such an extent that the sweat will reach up to the middle of the ears, so, when all the people are in that state, they will ask Adam for help (استغاثو), and then Moses, and then Muhammad (p.b.u.h) The sub-narrator added "Muhammad will intercede with Allah to judge amongst the people. He will proceed on till he will hold the ring of the door (of Paradise) and then Allah will exalt him to Maqam Mahmud (the privilege of intercession, etc.). And all the people of the gathering will send their praises to Allah. 

Now remember, people will run towards Prophets for help, clearly word Istighatha has been used in this hadith, this proves that had Istighatha been shirk then it could have never been allowed on Day of Judgment. All those Prophets would have rather told the people to run towards Allah alone rather than next Prophet! It is to be remembered that definition of shirk does not change due to life or death. When worship whether of someone alive or dead is shirk in both cases then how can seeking help be allowed during life and on day of judgment

In the end I would like to quote proofs from general verses of Qur'an

Qur'an states: 

إِيَّاكَ نَعْبُدُ وَ إِيَّاكَ نَسْتَعِينُ.

Translation: It is You we worship “AND” You we ask for help. [Sahih International: Al-Fatiha, Verse # 5]

 Shabbir Ahmad Uthmani a renowned deobandi scholar said in explanation of this verse: We get to know from this blessed verse that except for the Dhaat of Allah, asking help from anyone else in REALITY is absolutely not permissible. However if it is believed that the accepted (maqbool) person is just a means (Wasita), (he is) Allah's Rahmah, and Ghayr Mustaqil (not having indipendant personal powers), then to seek his Zahiri help is allowed. This seeking of help is actually seeking help from Allah. (Tafsir al Uthmani under Surah Fatiha Verse 5). 

If someone denies Shabbir Ahmad Uthmani because of being deobandi then look at Tafsir e Azizi of Shah Abdul Aziz Muhadith Dhelvi (rah) under this verse. He is a mutually agreed upon scholar. He has said similar. 

Anyways there are three very important points derived from this verse of Glorious Qur'an

(A) Allah differentiated between "worship" and "asking for help" by putting an “AND” in-between the two, so had worship and asking for help been the same things then Allah would not have differentiated between them by putting “WA” in-between, therefore different ruling shall apply on Istighatha depending on the nature of it whereas worship of any kind directed towards anyone other than Allah is an absolute polytheism/disbelief. 

(B) This verse proves that real help is from none but Allah. Whosoever believes that someone/something (like medicine) other than Allah provides “Haqeeqi (real)” and “independent” help then such a person is polytheist, so it should always be embedded in hearts and minds that the cause and effect is only created by Allah in all cases.

(C) This verse is general and does not differentiate between seeking help from an alive or dead. Hence same ruling shall apply in both cases, those who say that you can ask alive people for help but not pious people who have passed away, they have no proof whatsoever, but rather they misuse this verse by giving false interpretation. If their logic was correct then according to this verse even asking for help from alive should be shirk. It is to be noted here that making idols of someone alive or dead and worshipping them is shirk in both cases, whereas Salafis claim that asking for help from alive is allowed whereas shirk when we ask someone passed away. Had it been shirk to ask help from others then it would have been shirk in both scenarios. 

In Qur'an itself the Prophets have asked help from other than Allah at many occasions and the Awliya even did marvelous wonders, for example