Musnad Ahmad 937:143

Muhammad ibn Ja'far and Hajjaj narrated to us, they said: Shu'bah narrated to us, from Wasil al-Ahdab, from al-Ma'rur ibn Suwayd. Hajjaj said: I heard al-Ma'rur say: I saw Abu Dharr, and upon him was a garment—Hajjaj said: at al-Rabadhah—and upon his servant was the like of it. Hajjaj said another time: So I asked him about that, and he mentioned that he had insulted a man during the time of the Messenger of Allah (peace and blessings of Allah be upon him), and he shamed him for his mother. He said: So the man came to the Prophet (peace and blessings of Allah be upon him) and mentioned that to him. The Prophet (peace and blessings of Allah be upon him) said to him: "Indeed, you are a man in whom there is ignorance (Jahiliyyah). Your brothers are your servants (khawl); Allah has placed them under your hands. So whoever has his brother under his hand, let him feed him from what he eats, and let him clothe him from what he wears. And do not burden them with what overcomes them, and if you do burden them, then assist them with it."