Sahih Bukhari Volume 8, Book 80, Hadith Number 750.

Narrated By Al-Aswad : ‘Aisha said, “I bought Barira and her masters stipulated that the Wala would be for them.” ‘Aisha mentioned that to the Prophet and he said, “Manumit her, as the Wala is for the one who gives the silver (i.e. pays the price for freeing the slave).” ‘Aisha added, “So I manumitted her. After that, the Prophet caller her (Barira) and gave her the choice to go back to her husband or not. She said, “If he gave me so much and so much (money) I would not stay with him.” So she selected her own self (i.e. refused to go back to her husband).”