Musannaf Ibn Abi Shaybah

Hisham Hasan narrates that a man made a will, and after gathering people, said: If I die, I make you witnesses that my such-and-such slave is free. He was told: You have freed such-and-such slave, but you left the other such-and-such slave who served you more. Upon this, he said: Call the people again! And said to them: I make you witnesses that I have revoked the freedom of that slave, and the other such-and-such slave is free if I die. So, that man died, and the first slave claimed that he was free, and the second said that he was free. So, they went to Abdul Malik bin Marwan for a decision, and he rejected the freedom of the first slave and declared the freedom of the second slave.