Al-Husayn b. Ibrahim narrated to us. He said: `Ali b. Ibrahim narrated to us from his father Ibrahim b. Hashim from Abi’l Salt al-Harawi. He said:

Al-Ma’mun said to al-Rida : O son of the Messenger of Allah! I have recognized your virtue, your knowledge, your asceticism, your piety, and your worship, and I see that you are more rightful to the caliphate than myself. So, al-Rida said: Through my servitude to Allah, I become proud; and through my asceticism of this world, I hope to be delivered from the evil of this world; and through my piety in [abstinence of] the forbidden, I hope to win the spoils; and through my humility in this world, I hope to be elevated in the sight of Allah. So, al-Ma’mun said to him: Surely, I see that I should abdicate myself from the caliphate, give it to you, and pledge allegiance to you. So, al-Rida said to him: If the caliphate were yours, and Allah made it for you, then you would not be able to remove that which Allah has dressed you with and give it to someone else. If the caliphate were not yours, you would not be able to give me that which does not belong to you. So, al-Ma’mun said to him: O son of the Messenger of Allah! You must accept this affair. So, he said: I will never do that willingly. He did not stop demanding this daily until he gave up on having him accept it. So, he said to him: If you will not accept the caliphate, and you would not like me to pledge allegiance to you, then be my crown prince, so that you may have the caliphate after me. So, al-Rida said: By Allah, my father narrated to me from his forefathers from Amir al-Mu’minin from the Messenger of Allah (s) that I will leave this world before you, having been killed with poison and oppressed. The angels of the heavens and the angels of the Earth will weep for me, and I will be buried in an isolated land beside Harun al-Rashid. So, al-Ma’mun wept, then he said to him: O son of the Messenger of Allah! Who will kill you or want to harm you whilst I am alive? So, al-Rida said: If I wanted to tell you who will kill me, I would have said it. So, al-Ma’mun said: O son of the Messenger of Allah! You only want to lighten matters for yourself with these words and repel this affair from yourself, so that the people may say: “You are ascetic in this world.” So, al-Rida said: By Allah, I have never lied since my Lord created me, nor have I ever been ascetic of this world for this world. Surely, I know what you want. So, al-Ma’mun said: What do I want? He said: Will you grant immunity for an honest answer? He said: You are immune. He said: With this, you want the people to say: “Surely, `Ali b. Musa did not abstain from this world, but rather this world abstained from him – do you not see how he accepted the position of crown prince out of desire for the caliphate?” So, al-Ma’mun became angry, then said: Surely, you always treat me in a way that I hate, as though you are immune from me. I swear by Allah, you must accept the position of crown prince, or I will force you to do so. If you do not do so, I will strike your neck. So, al-Rida said: Allah has prohibited me from tossing my hand into peril, so if this is the condition, then do as you wish, and I will accept, so long that I do not appoint anyone or dismiss anyone, nor change any practices or traditions; and that I am just a distant advisor. So, he accepted that, and he made him his crown prince despite his dislike of that.