Sahih Muslim Book 27, Hadith 62
I saw Abu Dharr wearing clothes, and his slave wearing similar ones. I asked him about it, and he narrated that he had abused a person during the lifetime of Allah's Messenger (may peace be upoe. him) and he reproached him for his mother. That person came to Allah's Apostle (ﷺ) and made mention of that to him. Thereupon Allah's Apostle (ﷺ) said: You are a person who has (remnants of) Ignorance in him. Your slaves are brothers of yours. Allah has placed them in your hand, and he who has his brother under him, he should feed him with what he eats, and dress him with what he dresses himself, and do not burden them beyond their capacities, and if you burden them, (beyond their capacities), then help them.
" You are a person having the remnants of Ignorance in him." (these words also occur, that Abu Dharr) said: Even up to this time of my old age? He (the Holy Prophet) said: Yes. In the tradition transmitted on the authority of Abu Mu'awiya (the words are):" Yes, in this time of your old age." In the tradition transmitted on the authority of 'Isa (the words are):" If you burden him (with an unbearable burden), you should sell him (and get another slave who can easily undertake this burden)." In the hadith transmitted on the authority of Zuhair (the words are):" Help him in that (work)." In the hadith transmitted by Abu Mu'awiya (separately) there is no such word: Then sell him or help him." This hadith concludes with these words:" Do not burden him beyond his capacity."
It is essential to feed the slave, clothe him (properly) and not burden him with work which is beyond his power.