What did Prophet Muhammad (saw) tell Abu Dhar regarding treating his slave?
      Narrated Al-Ma'rur:                          At Ar-Rabadha I met Abu Dhar who was wearing a cloak, and his slave,      too, was wearing a similar one. I asked about the reason for it. He      replied, "I abused a person by calling his mother with bad names." The     Prophet said to me, 'O Abu Dhar! Did you abuse him by calling his      mother with bad names You still have some characteristics of      ignorance. Your slaves are your brothers and Allah has put them under      your command. So whoever has a brother under his command should feed      him of what he eats and dress him of what he wears. Do not ask them      (slaves) to do things beyond their capacity (power) and if you do so,      then help them.' "