Musannaf Ibn Abi Shayba 13:318

Yahya ibn Ya'la al-Taymi narrated to us, from Mansur, from al-Hakam, from Ali, that a man left his wife, his son, and his slave-girl. His wife and his son sold the slave-girl, and the one who bought her had intercourse with her, and she gave birth. Then the owner of the slave-girl came and laid claim to her, and he disputed with them before Ali. Ali said, "Your wife and your son sold her, and she has given birth to the man; the sale is valid." The man said, "I adjure you by Allah to judge according to the Book of Allah." So he (Ali) said, "Take your slave-girl and her child." And he said to the other (the buyer), "Take the woman and the son as compensation." When he took them, the other accepted the sale.