Musannaf Ibn Abi Shayba 13:1630

Abu Bakr narrated to us, he said: Shareek narrated to us, from Husayn ibn Abdullah, from Ikrimah, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Any man from whom his slave woman has given birth, she is then emancipated upon his death."