Musnad Ahmad 1153:1408

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from al-Hakam, from Ibrahim, from al-Aswad, from 'Aishah: That she wanted to purchase Barirah for the purpose of manumission, but her masters wanted to stipulate that her *wala'* (right of inheritance/patronage) would belong to them. She mentioned that to the Messenger of Allah, peace and blessings of Allah be upon him, and he said: "Purchase her, for the *wala'* belongs only to the one who manumits." He gave her the choice regarding her husband, and her husband was a free man. Meat was brought to the Prophet, peace and blessings of Allah be upon him, and it was said: "This is what was given as charity to Barirah." He said: "It is charity for her, and a gift for us."