Musannaf Ibn Abi Shayba 13:517

Abu Bakr narrated to us, he said: Jarir narrated to us, from Mansur, who said: I asked Ibrahim about a man who emancipated a man, then the emancipated one went and formed a *wala'* (patronage) relationship with someone else. He said: He does not have the right to do that, unless the emancipator gifts it to him.