Sahih Muslim — The Book of the Merits of the Companions — Hadith No: 6309
Translation
(Imam Zain-ul-'Abidin) 'Ali b. Husain reported that when they came to Medina from Yazid b. Mu'awiya after the martyrdom of Husain b. 'Ali (Allah be pleased with him) Miswar b. Makhramah met him and said to him:Is there any work for me which you ask me to do? I said to him: No. He again said to me: Would you not give me the sword of Allah's Messenger (ﷺ) for I fear that the people may snatch it from you? By Allah, if you give that to me, no one would be able to take it away, so long as there is life in me. Verily 'Ali b. Abi Talib sent a proposal of marriage to the daughter of Abu Jahl in spite of (the fact that his wife) Fatima (had been living in his house). Thereupon I heard Allah's Messenger (ﷺ) say while addressing the people on the pulpit. I was adolescing in those days. He said: Fatima is a part of me and I fear that she may be put to trial in regard to religion. He then made a mention of his son-in law who had been from the tribe of 'Abd Shams and praised his behaviour as a son-in-law and said: Whatever he said to me he told the truth and whatever he promised he fulfilled it for me. I am not going to declare forbidden what is lawful and make lawful what is forbidden, but, by Allah, the daaghter of Allah's Messenger and the daughter of the enemy of Allah can never be combined at one place