Musannaf Ibn Abi Shayba 13:1041

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Ayyub, from Humayd ibn Hilal, that a man among them gave a slave woman as charity to his mother, then she (the mother) made a *kitabah* (contract of manumission) with her. Then his mother passed away, so he asked ‘Imran ibn Husayn. He said: "You inherit from your mother, and if you wish, you may direct her (the slave woman) in the same direction you had directed her before." Humayd said: "I have indeed seen her, and it is said to her: Lubaynah."