I saw Abu Dharr (May Allah be pleased with him) wearing a nice gown, and his slave was also wearing one similar to it. I asked him about it, and he said that he had exchanged harsh words with a person during the lifetime of the Messenger of Allah (ﷺ) and put him to shame by making a reference to his mother. That person came to the Messenger of Allah (ﷺ) and made mention of that to him. Thereupon the Messenger of Allah said, "You are a person who has remnants of the 'Days of Ignorance' in you. Your slaves are your brothers. Allah has placed them under your authority. He who has his brother under him, should feed him from whatever he eats, and dress him with whatever he wears, and do not burden them (assign burdensome task to them) beyond their capacity; and if you burden them then help them."

[Al- Bukhari and Muslim].