Musannaf Ibn Abi Shayba 13:1640

Abu Bakr narrated to us, he said: Ibn Fudayl narrated to us, from Ash'ath, from Salim, from Ibn Abi 'Aruba, from Ibn Abbas, that he used to make the *umm al-walad* (a slave woman who has borne a child to her master) part of her child's share.