Musannaf Ibn Abi Shayba 9:1458

Ibn ‘Ulayyah narrated to us, from Muhammad ibn ‘Amr, who said: The son of Rafi‘ ibn Khadij narrated to me that Rafi‘ ibn Khadij married his daughter to his brother’s son, Rifa‘ah ibn Khadij. And she had been breastfed by a *umm walad* (a slave woman who bore a child for her master) other than the mother of the father of the one who married her.