Thul-Hijjah 9, 1239
1) Anyone who is acquainted with the biography of the holy Prophet (pbuh), especially researching his conduct while laying the foundations of the Islamic State and its legislative system, the establishment of its bases, the issuing of its codes and the organizing of its affairs on behalf of the Almighty Allah..., will find ‘Ali (as) the vizier of the Messenger of Allah (pbuh), his supporter against his foes, the custodian of his knowledge, the heir of his government, his vicegerent, and the one in charge after him. Whoever studies the statements and actions of the Prophet (pbuh), while at home or on a journey, will find his statements, peace and blessings of Allah Almighty be upon him and his progeny, sequential in this regard from the beginning of his Call till his demise.
2) Refer to such statements at the dawn of the Call, before Islam was preached in Mecca publicly, when the Almighty revealed unto him the verse
"And warn thy nearest tribe (Qur'an, 26:214)."
He invited them to the house of his uncle Abu Talib. They were forty men, more or less. Among them were his uncles Abu Talib, al-Hamzah, al-’Abbas, and Abu Lahab. The hadith in this regard is sequentially reported by Sunnis. At the conclusion of his statement to them, the Messenger of Allah, peace be upon him and his progeny, said:
"O descendants of ‘Abdul-Muttlib! I swear by God that I know no youth among the Arabs who has brought his people something better than what I have brought you. I have brought you the best of this life and the life to come, and God has commanded me to call you towards Him. Therefore, who among you shall support me in this matter and be my brother, the executor of my will, and my successor?"
All the listeners, with the exception of ‘Ali, who was the youngest among them, kept silent. ‘Ali responded by saying: "I, O Messenger of Allah, am willing to be your vizier in this matter." The Messenger of Allah (pbuh) then took ‘Ali by the neck and said: "This is my brother, executor of my will and vizier; therefore, listen to him and obey him." Those present laughed and kept saying to Abu Talib: "Allah has commanded you to listen to your son, and to obey him!"
3) Many of those who have learned the prophetic legacy by heart have reported the hadith above verbatim as such. Among them are: Ibn Ishaq, Ibn Jarir, Ibn Abu Hatim, Ibn Mardawayh, Abu Na’im, al-Bayhaqi in his book Al-Dala'il, both al-Tha’labi and al-Tabari in their exegeses of Surat al Shu’ara' in their book Al-Tafsir al-Kabir, in Vol. 2 of al-Tabari's Tarikh al-Umam wal Muluk.
Ibn al-Athir has reported it as an undisputed fact in Vol. 2 of his Al-Kamil when he mentioned how the Almighty commanded His Messenger to declare his call to the public, Abul-Fida in Vol. of his Tarikh while discussing who was the first to embrace Islam, Imam Abu Ja’far al-Iskafi al-Mu’tazili in his book Naqd al-Uthmaniyyah declaring its accuracy,1 al-Halabi in his chapter on the Prophet's hideout at the house of Arqam in his well-known Sirah.2
In this same context, with almost identical wording, has this hadith been reported by many masters of hadith and most reliable Sunni authorities such as al-Tahawi, Diya' al-Maqdisi in his Mukhtara, and Sa’id ibn Mansur in his Sunan. Refer to what Ibn Hanbal has recorded of ‘Ali's hadith on pages 111 and 159 of Vol. 1 of his Musnad. He also pointed out at the beginning of page 331 of Vol. 1 of his Musnad, to a very significant hadith from Ibn ‘Abbas] containing ten characteristics in which ‘Ali has distinguished himself from everyone else. That hadith is published in Nisa'i, too, from Ibn ‘Abbas, on page 6 of his Khasa'is al ‘Alawiyyah, and on page 132, Vol. 3, of Hakim's Mustadrak. Al-Thahbi has narrated it in his Talkhis], vouching for its authenticity. Refer to Vol. 6 of Kanz al-’Ummal which contains all the details.3 Refer also to Muntakhabul Kanz which is cited in the footnote of Imam Ahmad's Musnad; refer to the footnote on pages 41 and 43 of Vol. 5 of the book to find all details. This, we believe, suffices to serve as glorious proof, and peace be with you.