Abu 'Umar Zadhan said, "We were with Ibn 'Umar when he summoned
a slave of his whom he had beaten and he uncovered his back. 'Does it hurt?'
he asked. 'No,' he replied. Then he set him free. He picked up a stick
from the ground and then said, 'I do not have a reward (for him) worth
as much as this stick.' I asked, 'Abu 'Abdu'r-Rahman, why do you say this?'
He replied, 'I heard the Prophet, may Allah bless him and grant him peace,
say, "The expiation of someone who beats a slave more than he deserves
or slaps his face is that he must set him free."'"