Musannaf Ibn Abi Shaybah

Ibrahim (may Allah have mercy on him) said that if the pledger mortgages a slave and then sets him free, the slave will become free and the mortgagee will pursue the pledger.

Yahya bin Adam says that I asked Hasan bin Salih and Sharik about a person who mortgages a slave and then sets him free? They replied that setting him free is permissible, and Sharik says that the slave will strive to pay off the debt of the mortgagee, and Hasan says that striving for the mortgagee is not the responsibility of the slave.

It is narrated from Hazrat Ata (may Allah have mercy on him) that if a person buys a slave from another and then frees him before taking possession, he (Ata) said that it is not permissible to free him before taking possession.

Hazrat Sufyan says that if a person frees a slave, the slave will be released from mortgage, and if he makes him a mudabbar (a slave who will be freed after the master's death), he will also be released from mortgage. And if it is a bondwoman and he has intercourse with her and she bears a child, she too will be released from mortgage. Then, if the master is wealthy, the mortgagee will seize the master, and if the master is poor, these people (the slave and the bondwoman) will strive for the price and mortgage, whichever is less in value. Hazrat Sufyan says that then the slave will refer to his master for as much as he has strived (i.e., he will receive that much money or value from him), but umm walad (a bondwoman who has borne a child) and mudabbar will not refer to the master because their service is for the master.