Musannaf Ibn Abi Shayba 13:122

Waki’ narrated to us, from Mis’ar and Sufyan, from Salamah ibn Kuhayl, from al-Mustawrid ibn al-Ahnaf: He said: A man came to Abdullah and said, "My paternal uncle married me to his slave girl, and he wants to enslave my child." He said: "He does not have the right to do that."