Ali bin Abu Talib proposed to marry the daughter of Abu Jahl while still married to Fatimah. I heard the Messenger of Allah ﷺ addressing the people about this matter from his pulpit, and I was a young man approaching maturity at the time. He said, "Fatimah is a part of me, and I fear she may be tested in her faith."He then mentioned a son-in-law of his from the clan of Abd Shams and praised him highly for his conduct as a son-in-law, saying, "He spoke to me and was truthful with me, and he made promises to me and fulfilled them. I do not forbid what is lawful nor permit what is unlawful, but by Allah, the daughter of the Messenger of Allah ﷺ and the daughter of the enemy of Allah shall never be joined together in one place."
أن علي بن أبي طالب، خطب بنت أبي جهل على فاطمة، فسمعت رسول الله ﷺ وهو يخطب الناس في ذلك على منبره هذا، وأنا يومئذ محتلم، فقال: إن فاطمة مني، وإني أتخوف أن تفتن في دينها. قال: ثم ذكر صهرا له من بني عبد شمس، فأثنى عليه في مصاهرته إياه فأحسن، قال: حدثني فصدقني، ووعدني فأوفى لي، وأني لست أحرم حلالا ولا أحل حراما، ولكن والله لا تجتمع بنت رسول الله ﷺ وبنت عدو الله مكانا واحدا أبدا.
Bukhari narrated it in the Book of the Fifth Share (3110), and Muslim narrated it in the Virtues of the Companions (2449-95), both through Yaqub bin Ibrahim, who said, Our father narrated to us from Walid bin Kathir, who said, Muhammad bin Amr bin Halhala Duali narrated to me that Ibn Shihab told him that Ali bin Husayn told him, and Miswar bin Makhrama narrated it to him, and he mentioned it, and it includes a story.This is Muslim's wording, and Bukhari's wording is similar to it.