Muwatta Imam Malik (Riwayat Yahya)

Imam Malik, may Allah have mercy on him, said that if a person makes his slave a mukatab (one who has a contract for freedom), then the mukatab dies and leaves behind an umm walad (a slave woman who has borne a child to her master), and leaves behind enough wealth to fulfill the contract of kitabah, then that umm walad will become the slave of the mukatab’s master, because the mukatab was not free at the time of his death, nor did he leave behind any offspring by whom the umm walad would also become free.

Imam Malik, may Allah have mercy on him, said that if a mukatab frees his slave, or gives some of his wealth in charity, and the master is not informed of this until the mukatab becomes free, then after his freedom, the mukatab cannot invalidate that charity or emancipation. However, if the master is informed of it before the mukatab's freedom and does not give permission, then that charity or emancipation becomes void. In this case, it is not obligatory for the mukatab to free that slave again or give charity after his freedom, but he may do so willingly.