Harun al-Rashid ordered Imam Musa, peace be on him, to be arrested, and he stayed in prison for many years. Then he ordered him to be brought in his palace. When he was brought and sat down, Harun al-Rashid turned to him and angrily asked him:
- Musa b. Ja‘far, are land taxes collected for two caliphs?
- Commander of the faithful, I seek refuge for you with Allah that you should bear the sin committed against me and your own sin, and that you accept falsehood from our opponents against us. You have come to know that lies have been fabricated against us since the death of Allah’s Apostle, may Allah bless him and his family; you have knowledge of that. I ask you through your kinship to Allah’s Apostle, may Allah bless him and his family, to permit me to relate to you a tradition related to me by my father on the authority of his forefathers on the authority of my grandfather, Allah’s Apostle, may Allah bless him and his family.
- I have given you permission.
- My father has told me on the authority of his forefathers on the authority of my grandfather, Allah’s Apostle, may Allah bless him and his family, that he has said: “Surely when kinship touches kinship, it moves and shakes.” Therefore, give me your hand!
Accordingly, Harun felt pity (for him) and his anger disappeared. He stretched out his hand to him, drew him towards him, and embraced him for a long time; then he brought him nearer to him while his eyes were bathed in tears; he turned to him and said to him some words full of sympathy:
- You and your grandfather are truthful. My blood has moved and my veins have shaken to the extent that compassion has dominated me and my eyes has flowed with tears. I want to ask you about something that has been on my mind for a time; I have asked none about it. If you answer me about it, I will release you and do not accept the words of anybody against you. I have been informed that you never tell lies; therefore, tell me the truth about what I ask you.
- If I had knowledge of it and you gave me security, I would tell you about it.
- I would give you security if you told me the truth and left the precautionary dissimulation for which you had been known, O Fatima’s sons.
- Ask me about whatever you wish.
- Why have you been given preference over us while you and us belong to one tree, the Banu ‘Abd al-Muttalib, we, and you are one (tree), so the Banu al-‘Abbas and you are the children of Abi Talib. They are two uncles of Allah’s Apostle, may Allah bless him and his family, and they have the same kinship to him?
- We are nearer to him.
- Why is that?
- That is because ‘Abd Allah and Abi Talib belong to one father and mother; your father al-‘Abbas does not belong to the mother of ‘Abd Allah and Abi Talib.
- Why have you claimed that you have inherited the Prophet, may Allah bless him and his family, and (that) the uncle veils the cousin, and Allah’s Apostle, may Allah bless him and his family, has died, and Abu Talib had died before him, and al-‘Abbas, his uncle, was alive?
- I ask the commander of the faithful to exempt me from it and to question me about all chapters other than it.
- No, you should answer (it)!
- Give me security.
- I had given you security before the speech.
- It has been mentioned in the speech of (Imam) ‘Ali, peace be on him: “None, male or female, has (the right) to share (the inheritance) with the child of the backbone (sons, daughters, and grandsons) except the parents, the husband, and the wife. It has not been established that the uncle shares the inheritance with the child of the backbone. However, Taym, ‘Adi, and the Umayyads have said that the uncle is a father; that is their (personal) opinion without a reality and no tradition (reported) on the authority of the Prophet, may Allah bless him and his family.”
Then Imam Musa, peace be on him, mentioned to him a group of the jurists of the time who gave a religious decision on this matter similar to that his grandfather, (Imam ‘Ali) the Commander of the faithful, peace be on him, had given. He, peace be on him, has added his speech to that: “The earlier general populace have narrated on the authority of the Prophet, may Allah bless him and his family, that he has said: ‘‘Ali is the most capable of you in giving legal decisions.’” Similarly, Umar b. al-Khattab has said: ‘‘Ali is the most capable of us in giving legal decisions.’ And it (judgement) is a comprehensive noun, for it includes all things such as recitation (of the Qur’an), religious duties, and knowledge through which the Prophet, may Allah bless him and his family, praised his companions.”
After Imam Musa, peace be on him, had given this irrefutable proof, Harun al-Rashid asked him to give him more explanations, so he, peace be on him, said: “Surely the Prophet did not bequeathed those who did not emigrate and did not establish their pledge of allegiance until they emigrated.”
Harun asked: “What is your proof?”
He, peace be on him, said: “These words of Him: and (as for) those who believed and did not fly, not yours is their guardianship until they fly. And my uncle al-‘Abbas did not emigrate.”
Harun turned yellow and burst with anger, so he said to the Imam:
-Have you told any of our enemies or our jurists about that?
- No, and none had told me about it except you.
He calmed down and asked:
-Why have you permitted the non-Shi’ites (‘amma) and the Shi’ites (khassa) to ascribe you to the Prophet, may Allah bless him and his family, and to call you: O Sons of Allah’s Apostle, and you are the sons of ‘Ali, and one is ascribed to his father, and Fatima was a container, and the Prophet, may Allah bless him and his family, is your grandfather on the side of your mother?
- If the Prophet, may Allah bless him and his family, was raised from the dead and proposed to your daughter, would you respond to him?
- Glory belongs to Allah! And why do I not respond to him? Rather I would through that pride myself on the Arabs, the non-Arabs, and Quraysh
- But he would not propose (to my daughter) and I would not marry (her) to him.
- Because he begot me and did not beget you.
- Well-done, Musa!
- Why have you said that you are the Prophet’s progeny, while the Prophet had no progeny, the progeny belongs to the male and not to the female, and you are his daughter’s children?
- I ask you, by the right of the kinship, to exempt me (from that)
- No, you should tell me about your proof, O ‘Ali’s sons, and you are, Musa, their chief and the Imam of their time; I do not exempt you (from that).
- Will you give me permission to answer?
- Give (me the answer).
- Allah has said in his book: and of his descendants, Dawud and Sulayman and Ayyub and Yousif and Harun; and thus do We reward those who do good (to others). And Zakariya and Yehya and Isa and Ilyas; every one was of the good. Who is ‘Isa’s father, O Commander of the faithful?
- ‘Isa had no father.
- Allah has ascribed him to the descendants of the prophets through Maryam; similarly, we have been ascribed to the descendants of the Prophet, may Allah bless him and his family, through our mother Fatima, peace be on her.
Nevertheless, Harun asked Imam Musa to give him more evidence and proofs. So he, peace be on him, responded to him, saying: “Allah, the Great and Almighty, has said: But whoever disputes with you in this matter after what has come to you of knowledge, then say: Come, let us call our sons and your sons and our women and your women and our near people and your near people, then let us be earnest in prayer, and pray for the curse of Allah on the liars. None claims that the Prophet, may Allah bless him and his family, made someone enter under the cloak (kisa’) when he challenged the Christians to a contest of prayer to Allah mubahala) except ‘Ali b. Abi Talib, Fatima, al-Hasan, and al-Husayn. Therefore the explanation of the words of Him, the Exalted, is: Our sons are al-Hasan and al-Husayn; our women is Fatima; our near people is ‘Ali b. Abi Talib, peace be on him. He has added another proof to this proof: “Surly the (religious) scholars have unanimously agreed that Gabriel said on the Day of Uhad: ‘O Muhammed, surely this is the help from ‘Ali.’ So he (the Prophet), may Allah bless him and his family, has said: ‘Surely he (‘Ali) is of me and I of him.’ So he (Gabriel) has said: ‘And I am of you.’”
Harun stopped his argument and found no way to follow, for the Imam gave undoutable, conclusive arguments. (Bihar al-Anwar, vol. 12, pp. 274-275.)