Musannaf Ibn Abi Shayba 28:989

Muhammad ibn Bakr narrated to us, from Ibn Jurayj, who said: I said to 'Ata', "Free women whom the enemy captured, and a man purchased them—may he have intercourse with them?" He said, "No. He shall not enslave them, but he shall give them their own selves for what he purchased them for, and he shall not return them."