Sunan ad-Darimi

It is narrated from Alaa bin Abdur Rahman, from his father, who said: My mother was a freed slave woman of the tribe of Harqah, and my father, Yaqub, was a mukatab (contracted slave) of Malik bin Aws bin Hadthan Nasri. Then my father paid the agreed amount for his manumission. So a man from Harqah came to Uthman (may Allah be pleased with him), and at that time Aws bin Malik was also sitting with him. The man from Harqah claimed my right, meaning the right of wala’ (allegiance/gift), and said: "He is my freed slave." Both of them sought a judgment from Uthman (may Allah be pleased with him), so he ruled in favor of the man from Harqah, that is, he ruled in favor of the mawali (clients) of the mother, not the mawali of the father.