It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that if a mukatab (a slave contracted to buy his freedom) is set free (and someone kills him), the Prophet (peace and blessings be upon him) ruled regarding him that for the portion of the contract he has paid, he will be given the blood money of a free man, and for the portion that remains unpaid, for which he is still a slave, the blood money of a slave will be given.