Musannaf Ibn Abi Shayba 13:2436

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Musa ibn Sa'id, that his grandmother died while at the house of Abu Burdah, and Abu Burdah took possession of some of her slave girls. I said: Did Ibn 'Awn narrate to you from Muhammad, that he said: "If a man wants to take the slave girl of his child while they are young, he should have her valued for him at her price and bear witness to her price"? He said: "Yes, I heard it."