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.' "
Narrated Al-Ma'rur bin Suwaid: I saw Abu Dhar Al-Ghifari wearing a cloak, and his slave, too, was wearing a cloak. We asked him about that (i.e. how both were wearing similar cloaks). He replied, "Once I abused a man and he complained of me to the Prophet (ﷺ) . The Prophet (ﷺ) asked me, 'Did you abuse him by slighting his mother?' He added, 'Your slaves are your brethren upon whom Allah has given you authority. So, if one has one's brethren under one's control, one should feed them with the like of what one eats and clothe them with the like of what one wears. You should not overburden them with what they cannot bear, and if you do so, help them (in their hard job).