H 81 - Muhammad bin Abdullah bin Hasan Aftas said:

One day I was drinking wine with Mamun, till he became intoxicated; his friends left, but he retained me. After that he brought out the slave girls and they played musical instruments and sang. Mamun said to one of them: If you had only sung for one who is settled in Tus. The slave girl recited the following dirge: 1- Being quenched with the land of Tus and one from the progeny of the Prophet who is located there, who has left grief and sorrow for us. 2- I mean Abul Hasan, who is the hope of all. He has right on all who express their grief and sorrow. Muhammad bin Abdullah says: Mamun wept so much that I also started crying. After that he said: Woe be on you, Muhammad, do the people of my house and people of your house consider that it is my duty to appoint Abul Hasan as heir apparent? By Allah, if he had not died, I would definitely have appointed him as my successor [whereas it was Mamun himself who got the Imam martyred], but he passed away so soon. May Allah curse the two sons of Hasan; Abdullah and Hamza, who killed him. Then he said: O Muhammad bin Abdullah, by Allah, I am quoting a strange tradition for you. Keep it confidential. I said: Chief of believers, what tradition is that? He replied: When Zahiriya became pregnant with my son, Badr, I went to Imam Ridha and said: May I be your ransom, I have received information that Musa bin Ja’far, Ja’far bin Muhammad, Muhammad bin Ali, Ali bin Husain and Husain bin Ali used to resort to divination and did not make any mistake in it. You are their successor and their knowledge has come to you and I am also too much fond of Zahiriya and don’t prefer any of my slave girls to her. She has had many miscarriages. Do you have any solution for this? Imam Ridha said: Do not fear miscarriage. Very soon Zahiriya would give birth to a healthy child that would resemble its mother the most and the Almighty Allah has added two things in his creation and it is that it will have an extra finger in both its hands and feet. I said to myself: By Allah, this is a good opportunity that if the circumstances proved against his prediction, I will remove him from heir apparency. Therefore, I was eager for this delivery till Zahiriya got labor pains. I said to the nurse: After the delivery, bring the newborn to me, whether it is a boy or a girl. [After sometime] The nurse brought to me a newborn child with the same characteristics and the boy was glowing like the moon. [Seeing this] I decided that I would leave Caliphate and all the matters of governance to him, but he did not accept. I gave my seal ring to him and said: Please take the matters of governance in your control and you have precedence [in Caliphate] and I will not oppose you at all. By Allah, if he had accepted, I would have done that.