Maliks Muwatta Book 29, Hadith Number 25.

Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahman from al-Qasim ibn Muhammad that A’isha umm al-muminin, said, “There were three sunnas established in connection with Barira| firstly was that when she was set free she was given her choice about her husband, secondly, the Messenger of Allah, may Allah bless him and grant him peace, said about her, ‘The right of inheritance belongs to the person who has set a person free,’ thirdly, the Messenger of Allah, may Allah bless him and grant him peace, came in and there was a pot with meat on the boil. Bread and condiments were brought to him from the stock of the house. The Messenger of Allah, may Allah bless him and grant him peace, said, ‘Didn’t I see a pot with meat in it?’ They said, ‘Yes, Messenger of Allah. That is meat which was given as sadaqa for Barira, and you do not eat sadaqa.’ The Messenger of Allah, may Allah bless him and grant him peace, said, ‘It is sadaqa for her, and it is a gift for us.'”