The Children of the Holy Prophet of Allah
Imam Musa ibn Ja'far (A.S.) says:
"All people are blessed by Allah's mercy as long as they treat each other kindly, interact trustworthily, and behave honestly and justly."
One day, Harun al-Rashid – the Abbasid Caliph- asked some questions from Imam Kadhim (A.S.) through a debate between him and the Imam. Imam Kadhim (A.S.) answered all his questions. As his last question, Harun al-Rashid asked: "Why do you allow people to attribute you to Prophet Muhammad (S.A.W.) and call you as the Progeny of the Messenger of Allah (S.A.W.), while you are the progeny of Ali ibn Abi Talib (A.S.). Clearly enough everyone relates himself to his father and the Prophet (A.S.) is your grandfather from the mother side!"
Imam said: "Would you marry your daughter to the Prophet, if he was alive and asked for your daughter's hand in marriage?"
Harun said: "Why not? Certainly I do. I would definitely be proud of this; I will boast of it to all Arabs, non-Arabs and Quraish."
Imam said: "But if he was alive, I would not do that."
Harun Asked surprisingly: "Why?!"
Imam Musa ibn Ja'far (A.S.) said: "Because he is my father (even from mother side), but he is not your father. So I can consider myself as the descendant of Allah's Prophet (S.A.W.)."
Harun asked again: "So why do you consider yourself from the progeny of Prophet (S.A.W.) while the progeny is considered from father side, not from mother side. Please give me proof from the Holy Quran.
Then, Imam recited the following verses: "And We bestowed upon him [Ibrahim] Ishaq/Isaac and Yaqoub/Jacob; each of them We guided and Nuh/Noah We guided before, and of his descendants, Dawood/David and Sulaiman/Solomon and Ayub/Job and Yusuf/Joseph and Haroun/Aaron thus do We reward those who do good (to others). And Zakariya/Zachariah and Yahya/John and Isa/Jesus and Iliyas/Elias; Each one (of them) was of the righteous." (The holy Quran, 6:84, 85)
After reading these verses, the Imam (A.S.) addressed Harun: "Jesus (A.S.) is considered as the descendant of Ibrahim (A.S.) in this verse. Does he relate to Ibrahim from father side or mother side?"
Harun said: "According to the text of the Holy Quran, Jesus (A.S.) has no father."
Imam (A.S.) said: "So Jesus (A.S.) is considered as the descendant of Ibrahim (A.S.) from mother side. Similarly, we are considered as the descendant of the Prophet from our mother, Fatimah (A.S.). Do you want me to read another verse for you?
Harun replied: "For sure."
Then, Imam (A.S.) read the verse of Mubahilah: "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 ourselves and yourselves, then let us be earnest in prayer, and pray for the curse of Allah on the liars." (The holy Quran, 3:61)
After reading the verse, Imam (A.S.) said: "No one claims that the Prophet took any one else with him to the Mubahilah with the Christians of Najran, except Ali, Fatimah, Hasan and Hussain (Peace Be Upon Them). So Hassan (A.S.) and Hussain (A.S.) are the instances of Our Sons in this verse, despite being related to the Prophet from mother side and being son of his daughter.
Harun, who was surprised and had nothing to say, asked: "Do you have any request?" Imam Kadhim (A.S.) said: "No. I want to go back home…"
(Selection taken from: "The Practical Character and Behavior of Ahl al-Bayt (PBUT)", vol.9, by Sayyid Kadhim Arfa')