Zadhan says that once Sayyiduna Ibn Umar (may Allah be pleased with them both) called one of his slaves and set him free, and picking up a straw or something similar from the ground, he said: "I will not receive any reward for freeing him, not even equal to this straw. I heard the Noble Prophet (peace and blessings be upon him) say: Whoever slaps his slave, its expiation is that he should set him free."