Musannaf Ibn Abi Shayba 13:1633

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Al-A’mash narrated to us, from Zayd ibn Wahb, who said: A man from the tribe died and left behind an *umm walad* (a slave woman who has borne a child for her master). Al-Walid ibn ‘Uqbah stood up to sell her. We came to ‘Abdullah ibn Mas’ud and asked him. He said: "If you must do it, then make it [the price] from the share of her son."