The Muslim scholars...
The Muslim scholars, regardless of their inclinations and doctrines, have unanimously agreed that Imam ‘Ali was the most knowledgeable of the people after the Prophet, may Allah bless him and his family, in the affairs of the Islamic law, the precepts of religion, the affairs of policy, army, and society. The community embraced Islam for the first time.
It was, first of all, in need of explaining the beauties of the precepts of the Islamic law and detailing the social matters such as contracts, inheritances, and punishments. It is natural that if Imam ‘Ali had not been appointed to undertake the office of the Imamate, the community would have been deprived of his outstanding merits.
This is rationally impossible for the Prophet, may Allah bless him and his family, who took great care of his community and was kind to it, as Allah, the Exalted said: “Certainly an Apostle has come to you from among yourselves, grievous to him is your falling into distress, excessively solicitous respecting you, to the believers (he is) compassionate, merciful.[^1]” As for the traditions which were reported on the authority of the Prophet, may Allah bless him and his family, concerning the Imamate of Imam ‘Ali, the Commander of the faithful, peace be on him, they are numerous.
The narrators and the historians have unanimously agreed on them. The most important one of them is the hadith of al-Ghadir in which the Prophet, may Allah bless him and his family, appointed Imam ‘Ali as successor after him and ordered the Muslims to pledge allegiance to him, saying: “Whoever I am the master (mawla) of, this man, ‘Ali, is his master.
O Allah, befriend whoever befriends him, be hostile to whoever opposes him, support whoever supports him and desert whoever deserts him.” Imam Zayn al-‘Abidin, peace be on him, was asked about the meaning of this tradition and he replied: “Allah’s Apostle told them about the Imam after him.[^2]” The Shi‘ite religious scholars and other scholars mentioned in their theological books unquestionable scientific proofs for the Imamate of the twelve Imams, peace be on them.
They indicated that the twelve Imams were the trustees of the Prophet, may Allah bless him and his family, to authority, that their behavior and laudable deeds indicated their Imamate and their general deputyship on behalf of the Apostle, may Allah bless him and his family.