Ahlus Sunnah believe that Sayyiduna Abu Bakr (RA) was the first appointed Caliph according to this following verse of Qur’an:

Those who hearken to their Lord, and establish regular Prayer; who (conduct) their affairs by mutual Consultation; who spend out of what We bestow on them for Sustenance (Yusuf Ali: 42:38)

This verse uses the wording “Shura Baynahum” i.e. mutual consultation. It is a fact according to Sunnis that Sayyiduna Abu Bakr (RA) was appointed as first caliph of Islam with mutual consultation of Mahajireen (migrants) and Ansar (helpers in Madina). According to Shias Sayyiduna Ali (RA) and some Sahaba disputed for a while on this issue but finally accepted Sayyiduna Abu Bakr (ra) as a caliph under compulsion.

According to Sunnis the issue of caliphate was left open by Prophet (Peace be upon him) i.e. Sahaba were to choose the most deserving person by consulting one another. It was not a Wasiyah (will) of Prophet (Peace be upon him) nor was it a divine decree. Whereas Shia believe that Imamah/Khilafah is a divine decree.

There is a long hadith in Sahih Bukhari which has come with “IDRAAJ (INTERPOLATION)” of Ibn Shihab al- Zuhri and it asserts that Sayyidah Fatima (a.s) died being angry with Abu Bakr (ra) and also that Sayyiduna Ali (a.s) was not consulted on caliphate issue due to which he gave Bay’ah (pledge) after 6 months.

The Hadith having those wordings is weak according to Ahlus Sunnah due to interpolation (Idraaj) of al- Zuhri.

We should remember that history has reached Shias and Sunnis through different channels. Neither Shia nor Sunnis were present in those times hence reports cannot be verified to certainty. The only certain book is the Glorious Qur’an and nowhere does the Qur’an mention Caliphate disputes between Sahaba and Ahlul Bayt. Had this issue been so important then Allah who is Aalim ul Ghayb (who knows future beforehand) would have mentioned it.

Plus we should not use straw man argumentation i.e. concocting beliefs of other party and then attributing it to them. According to Sunnis Sayyiduna Ali (RA) instantly gave Ba’yah (pledge) to Abu Bakr (RA).

Let us look at a Sahih hadith in this regard which proves that Sayyiduna Ali instantly gave Bay’ah on the hand of Abu Bakr (RA)

حدثنا أبو العباس محمد بن يعقوب ثنا جعفر بن محمد بن شاكر ثنا عفان بن مسلم ثنا وهيب ثنا داود بن أبي هند ثنا أبو نضرة عن أبي سعيد الخدري رضي الله عنه قال لما توفي رسول الله صلى الله عليه وسلم قام خطباء الأنصار فجعل الرجل منهم يقول : يا معشر المهاجرين إن رسول الله صلى الله عليه وسلم كان إذا استعمل رجلا منكم قرن معه رجلا منا فنرى أن يلي هذا الأمر رجلان أحدهما منكم والآخر منا قال فتتابعت خطباء الأنصار على ذلك فقام زيد بن ثابت فقال : إن رسول الله صلى الله عليه وسلم كان من المهاجرين وإن الإمام يكون من المهاجرين ونحن أنصاره كما كنا أنصار رسول الله صلى الله عليه وسلم فقام أبو بكر رضي الله عنه فقال : جزاكم الله خيرا يا معشر الأنصار وثبت قائلكم ثم قال : أما لو فعلتم غير ذلك لما صالحناكم ثم أخذ زيد بن ثابت بيد أبي بكر فقال : هذا صاحبكم فبايعوه ثم انطلقوا فلما قعد أبو بكر على المنبر نظر في وجوه القوم فلم ير عليا فسأل عنه فقال ناس من الأنصار فأتوا به فقال أبو بكر : ابن عم رسول الله صلى الله عليه وسلم وخنتنه : أردت أن تشق عصا المسلمين فقال : لا تثريب يا خليفة رسول الله صلى الله عليه وسلم فبايعه ثم لم ير الزبير بن العوام فسأل عنه حتى جاؤوا به فقال : ابن عمة رسول الله صلى الله عليه وسلم وحواريه أردت أن تشق عصا المسلمين فقال مثل قوله لا تثريب يا خليفة رسول الله صلى الله عليه وسلم فبايعاه

Translation: Abu Sa’eed al Khudri (RA) said: When the Prophet (Peace be upon him) passed away, the companions gathered at the place of Sa’d bin Ubadah which included Abu Bakr and Umar. A spokesperson from the helpers (Ansar) said: “You know that the Messenger of Allah (Peace be upon him) was from Mahajireen (emigrants) and his caliph must also be from them, we were the Ansar (helpers) of the Prophet (Peace be upon him) and we will be helpers of his caliph just as we were of Prophet”. Then Umar bin al Khattab (RA) stood up and said “This person from the Ansar says truth and if it was anything other than this then we would not give you a Ba’yah (allegiance)”,  then he held the hand of Abu Bakr and said: “This is your close companion so give pledge on his hand”. After this Umar along with emigrants and the helpers all gave pledge of allegiance on his hand. Abu Bakr stood on the pulpit and he looked at the faces of people present there but he did not see al Zubair (RA), so he called for him and he came. Abu Bakr told him: “O son of the Prophet’s aunt and his disciple do you want division in the cause of Muslims?”  Zubair said: “Not at all O Caliph of Allah’s Prophet” then he stood and gave him pledge of allegiance. Then he looked at the faces of people but did not see Ali so he called for Ali bin Abi Talib, who then came. Abu Bakr said to him: “O cousin of Allah’s messenger and husband of his daughter, do you want division among the Muslims?” Ali replied: “Not at all O Caliph of Allah’s messenger”, then he stood and gave him pledge of allegiance. [Mustadrak ala Sahihayn by Imam Hakim  # 4457 and al Sunan al Kubrah of Imam Bayhaqi  # 16583. The narrations are authentic]

So this hadith proves that Sayyiduna Ali (ra) also instantly gave Ba’yah to Abu Bakr (RA). Even if assuming that hadith which has come from al- Zuhri is authentic, then still it proves that Sayyiduna Ali (ra) gave Bay’ah after six months. Had Abu Bakr (ra) been an unlawful caliph or it was God given right of Ali to be caliph then Sayyiduna Ali would not have violated Qur’anic injunction but would have rather fought him just like Imam Hussain (RA) fought against fake caliphate of Yazid in spite of being outnumbered by Army of Yazid.

It is a fact that Sayyiduna Ali was the bravest Sahabi even braver than Imam Hussain (RA), hence it was not possible for him to accept Caliphate of Abu Bakr (RA) due to force or compulsion.

According to Qur’an disputing over Caliphate issue does not make any of the parties to be wrong.

The dispute on the issue of caliphate was not only in nation of Muhammad (Peace be upon him) but rather the “FIRST EVER DISPUTE IN HISTORY WAS ON CALIPHATE”

Qur’an states: And when your Lord said to the angels, I am going to place in the earth a khalif, they said: What! Wilt Thou place in it such as shall make mischief in it and shed blood, and we celebrate Thy praise and extol Thy holiness? He said: Surely I know what you do not know. (Shakir: 2:30)

The word “Khalifah” is used in this verse. Angels disputed over caliphate issue even though they are infallible. So even if assuming Sayyiduna Ali was infallible still it is not wrong of him to dispute over caliphate and none of the parties can be blamed.

Shias on the other hand use many proofs from within Sunni literature that Sayyiduna Ali (ra) deserved to be first leader and Caliph of Muslim nation. The biggest proof they use is the declaration of Prophet Muhammad (Peace be upon him) at a place called Ghadir Khumm.

Let us start with the shorter version of hadith:

Narrated Abu Sarihah, or Zaid bin Arqam - Shu'bah had doubt: from the Prophet (ﷺ): "For whomever I am his Mawla then 'Ali is his Mawla." [Jami’ at- Tirmidhi, Vol. 1, Book 46, Hadith 3713. Salafis have declared it Sahih in Dar us Salam version]

Let us now see another hadith:

مَا تُرِيدُونَ مِنْ عَلِيٍّ مَا تُرِيدُونَ مِنْ عَلِيٍّ إِنَّ عَلِيًّا مِنِّي وَأَنَا مِنْهُ وَهُوَ وَلِيُّ كُلِّ مُؤْمِنٍ بَعْدِي 

Translation: …"What do you want from 'Ali?! What do you want from 'Ali?! Indeed 'Ali is from me, and I am from him, and he is the ally (Wali) of every believer after me." [Jami’ at- Tirmidhi, Vol. 1, Book 46, Hadith 3712, declared Hasan (good) by Salafis in Dar us Salam version]

Let us now look at a longer hadith:

عن زيد بن أرقم رضي الله عنه, قال: لما رجع رسول الله صلى الله عليه وآله وسلم من حجة الوداع, ونزل غدير خم, أمر بدوحات فقمن, فقال: كأني قد دعيت فأجبت, إني قد تركت فيكم الثقلين, أحدهما أكبر من الآخر: كتاب الله تعالى, وعترتي, فانظروا كيف تخلفوني فيهما, فإنهما لن يتفرقا حتى يردا علي الحوض. ثم قال: إن الله عز وجل مولاي, وأنا مولى كل مؤمن. ثم أخذ بيد علي رضي الله عنه, فقال: من كنت مولاه فهذا وليه, اللهم! وال من والاه, وعاد من عاداه.

Translation: “It is narrated by Zayd bin Arqam: When Allah’s Messenger was returning after the Hajjat -ul- wada‘, he stayed at Ghadir Khum. He commanded that a canopy should be put up and so it was done. Then he said: It seems as if I am about to breathe my last which I shall accept. Indeed, I am leaving two important things in your midst which exceed each other in importance: One (is) Allāh’s Book and the other (is) my progeny. Now it is to be seen how do you treat both of them after me and they will not be separated from each other, and they will appear before me at the Fountain of kawthar. Then added: Surely Allah is my Master and I am the master of every believer. Then, holding ‘Ali’s hand, he said: One who has me as his master has this (‘Alī) as his guardian. O Allāh! Befriend him who befriends him (‘Alī) and be the enemy of one who is his enemy.”

Reference: Hakim narrated it in al- Mustadrak (3:109 # 4576); Nasa’i, as- Sunan  ul- kubra (5:45, 130 # 8148, 8464); Tabarani, al- Mu‘jam -ul- kabir (5:166 # 4969);  Ibn Abi ‘Asim related it briefly in as- Sunnah (p.644 # 1555).  

Nasa’i related it with a sound chain of authorities in Khasa’is ameer- il mu’mineen ‘Ali bin Abi Talib (pg.84, 85 # 76).      

Similar hadith is narrated by Hakim who graded it sahih (sound) according to the conditions of Bukhari and Muslim in al-Mustadrak (3:533 # 6272) and al- Dhahabi confirmed its soundness in Talkhees.

From these hadiths it stands established that Prophet (Peace be upon him) used two words i.e. Mawla and Wali. The Sunnis and Shias differ on the meaning of these words. The Shia claim that Prophet (Peace be upon him) made Sayyiduna Ali his successor in these hadiths, whereas Sunnis say that it is just a praise of Sayyiduna Ali and he being Mawla/Wali of all believers does not mean he shall be first caliph too.

There is however an authentic hadith too where Prophet (Peace be upon him) said: Ali is my Khalifa of all believers after me, the hadith states:

ثنا مُحَمَّدُ بْنُ الْمُثَنَّى ، حَدَّثَنَا يَحْيَى بْنُ حَمَّادٍ ، عَنْ أَبِي عَوَانَةَ ، عَنْ يَحْيَى بْنِ سُلَيْمٍ أَبِي بَلْجٍ ، عَنْ عَمْرِو بْنِ مَيْمُونٍ ، عَنِ ابْنِ عَبَّاسٍ ، قَالَ : قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لِعَلِيٍّ : " أَنْتَ مِنِّي بِمَنْزِلَةِ هَارُونَ مِنْ مُوسَى إِلا أَنَّكَ لَسْتَ نَبِيًّا ،[إِنَّهُ لا يَنْبَغِي أَنْ أَذْهَبَ إِلا] وَأَنْتَ خَلِيفَتِي فِي كُلِّ مُؤْمِنٍ مِنْ بَعْدِي

Translation: Ibn Abbas (ra) narrates that the Prophet (Peace be upon him) said about Ali (a.s): You are in same position in relation to me what Harun (a.s) was to Musa (a.s), except that you are not a Prophet. You are “MY CALIPH’ for all believers after me [Imam Ibn Abi Asim, Kitab as- Sunnah, Hadith # 1188. Published by Maktab al Islami. Nasir ud- din Albani declared the chain as “Hasan (good)”]

Sunnis reply to this hadith that Prophet (Peace be upon him) had made Sayyiduna Ali (a.s) as Khalifah only for a short while while he was going for Tabuk, but this was not a general order. 

In one hadith hadith shown above the Prophet (Peace be upon him) said: “It seems as if I am about to breathe my last”

From this it has to be accepted both by Sunnis and Shias that this was the last declaration by the Prophet which happened after Hajjat -ul- Wadda’

The hadiths about Ali being Mawla and Wali are mutawattir (multiply narrated to certainty) and denying a Mutawattir hadith is a severe heresy. Ibn Taymiyyah whom Salafis highly admire is known to have rejected these hadiths. Nasir al-Albani who is also an authority for Salafis replied to Ibn Taymiyyah’s rejection:

أنني رأيت شيخ الإسلام بن تيمية , قد ضعف الشطر الأول من الحديث , و أما 

الشطر الآخر , فزعم أنه كذب! و هذا من مبالغته الناتجة في تقديري من تسرعه 

في تضعيف الأحاديث قبل أن يجمع طرقها و يدقق النظر فيها

Translation: When I saw Sheikh ul Islam Ibn Taymiyah considering the Hadith (For whosoever I am Mawla then Ali is his Mawla) as weak/doubtful in its first half and “LIE IN ITS SECOND” then I had to write in length over this issue. In my viewpoint, the reason behind such exaggeration (of Ibn Taymiyah) was that he used to be hasty in deciding the inauthenticity of some Hadiths before seeing them properly [Silsilat ul Ahadith as- Sahiha, Volume No.4, Page No. 344]

Coming back to the topic, the Shia from this hadith and many others about Ghadir Khum declaration say that it was the last sermon of Prophet and he declared Ali as Mawla and Wali. They claim that it is irrefutable declaration that Ali was appointed as his successor.

The Shia also use the hadith of “Manzilah” as proof which has already been shown, however let us now see it from Sahih Bukhari:

Narrated Sa’d: Allah's Messenger (ﷺ) set out for Tabuk appointing `Ali as his deputy (in Medina). `Ali said, "Do you want to leave me with the children and women?" The Prophet (ﷺ) said, "Will you not be pleased that you will be to me like Aaron to Moses? But there will be no prophet after me." [Sahih Bukhari, Vol. 5, Book 59, Hadith 700]

It is also narrated by other Sahaba like Jabir bin Abdullah (RA)

From these hadiths the Shia say that Harun (a.s) was deputy of Musa (a.s) hence Ali is also Prophet Muhammad (Peace be upon him)’s deputy and Caliph. We should know that Harun (a.s) was himself a Prophet. Plus he was deputy of Musa (a.s) during the life of Musa (a.s). Whereas the Khalifa of Musa (a.s) after his death was Yusha bin Noon (a.s) and he was not from family of Musa (a.s).

Shia also use a verse from Qur’an which states:

Verily, your Wali (Protector or Helper) is Allah, His Messenger, and the believers, - those who perform As- Salat (Iqamat -as- Salat), and give Zakat, and they bow down (submit themselves with obedience to Allah in prayer). [Translation by Salafi Muhsin Khan/Hilali 5:55]

There are some hadiths in Sunni literature that the person who gave charity while bowing down as mentioned in this verse was Sayyiduna Ali (RA). Many Sunni scholars have declared those hadiths to be weak, however they are multiply narrated to an extent that they reach the status of Hasan or Sahih. Many Mufasireen have also applied this verse to Ali (RA)

There is a hadith in which the Prophet (Peace be upon him) said that you would not appoint Ali as a leader after me. Let us look at this hadith:

It was narrated that Ali (ra) said, it was said: O Messenger of Allah who should be appointed in charge after you are gone? He said: If you appoint Abu Bakr you will find him trustworthy, uninterested in worldly gains, seeking the hereafter. If you appoint Umar, you will find him strong and trustworthy and not fearing blame of anyone for the sake of Allah. If you appoint Ali “WHICH I DO NOT THINK YOU WILL DO” you will find him a guide and guided, he will take (you) on the straight path. [Musnad Ahmed bin Hanbal, Hadith # 859]

Imam al- Haythami after narrating it said:

رواه أحمد والبزار والطبراني في الأوسط ورجال البزار ثقات‏.‏

Translation: It is narrated by Ahmed, al- Bazzar, and at- Tabrani in his al- awsat. The men of al- Bazzar are all relied upon [Majma uz Zawa’id, (5/186), Hadith # 8909]

Imam al- Hakim has also narrated 2 similar hadiths one of which he authenticated whereas al- Dhahabi disagreed with him.

This hadith cannot be misused by Shias because the Prophet (Peace be upon him) has praised Abu Bakr (RA) and Umar (RA) in it too. However yes they can claim that Sahaba would not let Ali to become a caliph after him. Many Sunni scholars have declared this hadith to be weak, whereas there are different routes of it which proves asl (basis) for it.

Reconciliation: Due to such hadiths both Shia and Sunnis have a strong stance, but as history has reached us from different and contradictory sources, we cannot say for sure who is more truthful. The Shias and Sunnis should stop these old arguments and fights, as that would lead us away from unity. The Khulafa -e- Salasa (first three caliphs) are highly revered by Sunnis, therefore cursing or ridiculing them shall never lead to unity between us. Those Shia who do takfir on Sahaba are themselves removed from the folds of Islam. We agree that Ahlul Bayt were mistreated by rulers like Yazid bin Mu’awiya, Marwan, and others but the first three caliphs did not wage war on any of the Ahlul Bayt. We shall explain in detail how Ahlus Sunnah despises Yazid and his likes later on.

If assuming that first three caliphs were wrong then Qur’an teaches us not to speak badly even of idols of polytheists let alone highly revered personalities of Sunnis.

Qur’an states: Revile not those unto whom they pray beside Allah, lest they wrongfully revile Allah through ignorance. Thus unto every nation have We made their deed seem fair. Then unto their Lord is their return, and He will tell them what they used to do. (Pickthall: 6:108)

Hence Shias should stop cursing at Sahaba and end this dispute once and for all. We Sunnis highly respect Mawla Ali (alayh salam) and we accept all his attributes. The Author shall allocate a whole chapter on the merits of Sayyiduna Ali and also on Karbala incident.

There is a verse in Qur’an which has indisputable praise of Sayyiduna Abu Bakr (RA)

Qur’an states: If you do not aid the Prophet - Allah has already aided him when those who disbelieved had driven him out [of Makkah] as one of two, when they were in the cave and he said to his companion, "Do not grieve; indeed Allah is with us." And Allah sent down his tranquility upon him and supported him with angels you did not see and made the word of those who disbelieved the lowest, while the word of Allah - that is the highest. And Allah is Exalted in Might and Wise. (Sahih International: 9:40)

This verse on praise of Abu Bakr (RA) is irrefutable. Even many Shia scholars have praised Abu Bakr (RA) in explaining this verse.

Some Shia claim that Abu Bakr (RA) was scared for himself not for Prophet (Peace be upon him), hence this verse is not in praise of Abu Bakr (RA)

Let us settle the score by seeing some Shia commentaries: Rawh al Jinaan by Jamal ud din Shaykh Abul Futuh ar Razi (in 600 AH) with commentary of Abul Hasan Shirani, Published from Tehran, Volume 6 ,Page # 35, writes:

Persian: Haqiqtast wa Khilaaf Naist, Qiyaam do kast kay dar Ghar budand, Rasulullah bood wa abu bakr bood izhuma fil ghar

Translation: It is a reality and there is “NO DIFFERENCE” that there were only 2 persons in cave, one was Prophet and other Abu Bakr.

The same Shia scholar said: Huzni- oo bar paighambar bood i.e. his grief was for the Prophet not for himself. The Shia scholar then states that Prophet and Abu Bakr stayed in cave for three days…Abdur Rahman bin Abi Bakr used to bring food to the cave. Abu Bakr was not fearful for his own life but only for the Prophet because Quran has not said La Takhaf but rather said “LA TAHZAN” which means “DO NOT GREIVE. – End Quote

Even if assuming Sayyiduna Abu Bakr (ra) feared for himself then that is natural and it does not mean in any way that he was not praised in this verse.

Qur’an states: They (Moses and Aaron) said: "Our Lord! We fear lest he hasten with insolence against us, or lest he transgress all bounds, He said: "Fear not: for I am with you: I hear and see (everything).(Yusuf Ali: 20: 45, 46)