On the authority of Ishaq b. Ibrahim b. Isma`il b. Hammad b. Zayd who said:
A messenger was sent to Yahya b. Aktham and a number of my companions, when he (Yahya) was the chief justice, and he said: Amir al-Mu’minin [i.e. the caliph Ma'mun] has commanded me to bring 40 people with me at dawn tomorrow, all of them people of knowledge (of religion) who will understand what is said to them and are good in their answers. So name whomsoever you think will be right for what Amir al-Mu’minin requires.’
So we named a number for him and he mentioned a number, until the desired number was complete. He wrote down the names of people bidding (them) to hasten to come before daybreak and sent for one who was present and instructed him concerning that.
So we went to him early in the morning before the rise of dawn and found him dressed and sitting, waiting for us. He mounted (his animal) and we mounted with him, until we reached the door, and there, a servant was standing. When he saw us, he said: ‘O Abu Muhammad, Amir al-Mu’minin awaits you’. We entered and he bid us perform the salat (obligatory prayers). We began it and had barely completed it when the messenger came out and said: ‘Enter!’ We entered and there was Amir al-Mu’minin sitting on his couch…. – until he said:
Then he said: ‘I did not send for you for this but I am pleased to give you the happy news that Amir al-Mu’minin wishes to debate with you concerning the school of thought that he follows and through which he obeys Allah’.
We said: ‘Then let Amir al-Mu’minin do it, may Allah give him success’.
He said: ‘Amir al-Mu’minin obeys Allah on the basis that `Ali b. Abi Talib is the best of the Khulafa after the Messenger of Allah, blessings and salutations of Allah on him, and the most worthy of people as a successor to him’.
Ishaq said: I said: ‘O Amir al-Mu’minin, among us there are those who do not acknowledge what the Amir al-Mu’minin has mentioned regarding `Ali, and Amir al-Mu’minin had called us for a debate.’
He said: ‘O Ishaq, choose. If you wish me to question you I will question you, and if you wish to question then speak.’
Ishaq said: I seized the opportunity and said: ‘No but I will question you, Amir al-Mu’minin.’ He said: ‘Ask.’
I said: ‘How does Amir al-Mu’minin say that `Ali b. Abi Talib was the most excellent of people after the Messenger of Allah, and the most entitled of them to Khilafah after him?’
He said: ‘O Ishaq, inform me of people by what do they differ in superiority over each other so that it is said: So and so is better than so and so?’
I said: ‘By good deeds.’ He said: ‘You have said the truth.’
He said: 'Inform me of one whose companion excelled over him during the lifetime of the Messenger of Allah, blessings and salutations of Allah on him. Then, after the death of the Messenger of Allah, if the one who was surpassed performed better acts than the one who excelled during the time of the Messenger of Allah, does he catch up with him?'
He said: I bowed my head. He said to me: O Ishaq, you do not say: Yes. If you say yes, I will find for you in this age of ours one who is greater than him in jihad and Hajj and fasting and Salat and almsgiving.’
I said: ‘Yes indeed, Amir al-Mu’minin, he will not catch up.’
He said: ‘The person who has excelled during the time of the Messenger of Allah, blessings and salutations of Allah on him, will always be the possessor of excellence. Ishaq, do you relate the Hadith of al-Wilaya?’
I said: ‘Yes Amir al-Mu’minin.’ He said: ‘Relate it.’ I did and he said: ‘Ishaq, do you think that this hadith makes incumbent on Abu Bakr and `Umar what was not made incumbent on them?’
I said: ‘The people have said that the hadith was only because of something that occurred between Zayd b. Haritha and `Ali and he denied the authority (wala') of `Ali. So the Messenger of Allah, blessings and salutations of Allah on him, said: ‘Of whomsoever I am master (mawla) `Ali is his master. O Allah, befriend him who befriends him and be at enmity with him who is at enmity with him.’
He said: ‘At what occasion did he say this? Was it not after his departure from the Hajjat’ul Wida’?
I said: 'Yes indeed.'
He said: 'If Zayd b. Haritha was killed before Ghadir, then how do you accept this for yourself? Tell me; if you were to see a son of yours, for a period of fifteen years, saying: Oh people, my subservients are the subservients of my cousin - let it be known. Would you deny that he identified to the people what they do not deny and can not be ignorant of?'
I said: 'Yes indeed, by God'. He said: 'O Ishaq, do you deem your son in a way that you do not deem the Messenger of Allah, blessings and salutations
of Allah on him?'
Woe be to you, do not make your jurists your masters. Allah, Sublime is His mention, has stated in His Book:
"They have taken their rabbis and monks as lords apart from Allah (9:31)".
They did not pray for blessings on them, neither did they fast, and nor did they claim that they were lords, but they commanded them and they obeyed their command'.
(We have taken whatever we have needed from the narration which is long and of very great benefit).