Imam al-Shafi'i (may Allah have mercy on him) said: "Ibn Sa'id bin al-As (Sayyiduna Khalid bin Sa'id (may Allah be pleased with him)) married Sayyidah Umm Habibah bint Abi Sufyan (may Allah be pleased with her) to the Prophet (peace and blessings be upon him) while Abu Sufyan was alive, because she was a Muslim and Ibn Sa'id was also a Muslim, and Abu Sufyan had no guardianship over her, because Allah Almighty has cut off guardianship between the Muslims and the polytheists."
Urwah (may Allah have mercy on him) narrates from Sayyidah Umm Habibah (may Allah be pleased with her) that she was married to Ubaydullah bin Jahsh, and Ubaydullah died in the land of Abyssinia. Then the Negus married Umm Habibah (may Allah be pleased with her) to the Prophet (peace and blessings be upon him), paid four thousand as her mahr from his own side, and sent her to the Prophet (peace and blessings be upon him) with Shurahbil bin Hasanah (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13797