Sahih al-Bukhari 2565 | Hadith

(5) – باب إِذَا قَالَ الْمُكَاتَبُ اشْتَرِنِي وَأَعْتِقْنِي فَاشْتَرَاهُ لِذَلِكَ

(5) – If a Mukatab slave asks somebody to buy and free him