Musannaf Ibn Abi Shayba 13:1653

Abu Bakr narrated to us, he said: Isra'il narrated to us, from Jabir, from 'Amir, Salim, al-Qasim, and 'Ata', regarding a slave who gave a man wealth, so he bought him and then emancipated him. They said: It is not permissible.