Musannaf Ibn Abi Shayba 13:1102

Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Sa’id, from Qatada, from Khallas, that a slave woman came to a tribe and claimed that she was free, so a man married her. Then, her master appeared and found her. Uthman judged that she and her children belonged to her master, and he assigned to her husband what he could recover of her dowry (or goods), and he established regarding them the Sunnah or the rule: for every head, two heads.