Muwatta 2365

Malik said: the sale of a conditionally freed slave is not lawful, and no one may buy him, unless the conditionally freed slave buys himself from his master, which is lawful for him, or someone gives money to the master of the conditionally freed slave and the master who conditionally freed him frees him, which is lawful too. His clientage belongs to the master who conditionally freed him. ¹

Belongs to the Muwatta, Book of the Conditionally Freed Slave (mudabbar). Source: the Muwatta. Mentions Malik ibn Anas. Built on in the chapters on conditional freedom (tadbir) and clientage (wala).