Muwatta 2282

Malik said of a Jew or Christian whose slave becomes Muslim, and who frees him before he is sold: the freed slave's clientage belongs to the Muslims, and does not return to his unbelieving master after his conversion. But if an unbeliever freed a slave of his own religion, then the freed slave became a Muslim before his manumitter, and the manumitter then became a Muslim, the clientage returns to him, because it was established for him on the day of manumission. If the unbeliever had a Muslim child, he inherits his father's clients in the first situation; but if the freed slave was a Muslim at the time of manumission, the unbeliever's child has no part of his clientage. ¹

Belongs to the Muwatta, Book of Manumission and Clientage. Source: the Muwatta. Mentions Malik ibn Anas. Built on in the chapters on clientage (wala).