Musannaf Ibn Abi Shaybah

A case was brought to Hazrat Umar (may Allah be pleased with him) that a mukatab (contracted slave) had brought his entire payment for his freedom at once, but the master said, "I will not accept it all at once. I made him a mukatab so that I could receive the payment gradually over two years as my livelihood, and during this period, if he dies, I would become his heir." Hazrat Umar ordered that the money be taken from him and placed in the public treasury (Bayt al-Mal), then given to his master in installments, and he decreed freedom for the slave.