Musannaf Ibn Abi Shaybah 32769 — A man who makes a bequest and then

Hisham narrates from al-Hasan that a man made a bequest, called some people and said: "If death comes to me, I call you to witness that such-and-such a slave of mine is free." It was said to him: "You have freed such-and-such a slave, but you have left out such-and-such other slave, who served better than him." At this he said: "Call the people back!" And he said to them: "I call you to witness that I have withdrawn from the freeing of this slave, and that such-and-such other slave is free if I die." Then the man died. The first slave claimed: "I am free," and the other said: "I am free." So they went to Abd al-Malik bin Marwan for a judgment, and he rejected the freeing of the first slave and declared the freeing of the other.