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."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / Q13797
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
Muhammad bin Ishaq (may Allah have mercy on him) said: I was informed that the guardian in the marriage of Sayyidah Umm Habibah (may Allah be pleased with her) was her cousin, Khalid bin Sa'id bin al-As (may Allah be pleased with him).
The Shaykh (may Allah have mercy on him) said: He was the son of her father's paternal cousin, because Sayyidah Umm Habibah (may Allah be pleased with her) is the daughter of Abu Sufyan bin Harb bin Umayyah, and al-As is the son of Umayyah.
(b) It has also been said that Sayyiduna Uthman bin Affan (may Allah be pleased with him) was the guardian of her marriage.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13798
Abu al-Aswad narrates from Urwah (may Allah have mercy on him) that the marriage of Umm Habibah (may Allah be pleased with her) was arranged by Uthman bin Affan (may Allah be pleased with him) in the land of Abyssinia.
(b) Al-Zuhri (may Allah have mercy on him) also said the same, as has been mentioned earlier; and Uthman bin Affan bin Abi al-As bin Umayyah: whichever of the two of them arranged the marriage, the guardianship (wilayah) stands; a difference is found regarding the third.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13799
Abu Zumayl narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Muslims would not even pay attention to Abu Sufyan, nor would they sit with him. He said to the Prophet (peace and blessings be upon him): "O Prophet of Allah (peace and blessings be upon him), I offer you three things: (1) I have the most beautiful and lovely daughter among the Arabs (Umm Habibah); I will marry her to you. (2) Appoint Mu'awiyah, who is my son, as your scribe of revelation. (3) And appoint me as a commander so that I may fight the disbelievers just as I used to fight against the Muslims." All three times he (peace and blessings be upon him) said: "Yes." Abu Zumayl said: Had he not asked the Prophet (peace and blessings be upon him) for these things, he would not have given them to him, because whenever he (peace and blessings be upon him) was asked for anything, he would only say "Yes."
Bukhari left this hadith out; he did not use Ikrimah bin Ammar as evidence in his Sahih, and he said: He had no book, so his hadith became disordered (mudtarib).
The Shaykh (may Allah have mercy on him) said: This hadith concerns the story of Sayyidah Umm Habibah (may Allah be pleased with her), but the scholars of the military expeditions (maghazi) are unanimous on the contrary, for they agree that the marriage of Sayyidah Umm Habibah (may Allah be pleased with her) took place before Sayyiduna Ja'far bin Abi Talib (may Allah be pleased with him) and his companions returned from Abyssinia, and they returned at the time of Khaybar; so the marriage of Sayyidah Umm Habibah (may Allah be pleased with her) had already taken place before that, while Abu Sufyan accepted Islam in the year of the Conquest of Makkah, two or three years after the marriage. How then can it be correct that her marriage happened because of Abu Sufyan's request? If it was based on a request, that is possible during one of his journeys to Madinah while he was still a disbeliever, when he heard the news of the death of Sayyidah Umm Habibah's (may Allah be pleased with her) husband; and the other two requests took place after he accepted Islam. If the hadith is preserved, it cannot bear any meaning other than this, and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13800