Bayhaqi 15776 — Reports on the owner treating his slaves equally

Al-A'mash narrates from Ma'rur that he said: We came to al-Rabadhah and saw that Sayyiduna Abu Dharr (may Allah be pleased with him) was wearing a hullah (suit), and his slave was wearing a similar hullah. We said: If only you had taken the cloth from the slave and made a fine hullah for yourself, and given the slave another garment. Sayyiduna Abu Dharr (may Allah be pleased with him) said: I will tell you a hadith. I abused a man by saying that his mother was a non-Arab, and he went to the Messenger of Allah (peace and blessings be upon him) and complained about me. I also came, and he (peace and blessings be upon him) asked me: "Did you really abuse him and mention his mother?" I replied: Yes, O Messenger of Allah (peace and blessings be upon him)! And in abuse, mention of the mother or father does come up. He (peace and blessings be upon him) said: "Abu Dharr! There is still some ignorance (jahiliyyah) in you." I said: Even at this old age of mine? He said: "Yes." And he said: "They are your brothers whom Allah has placed under your authority, so treat them well. Feed them, give them to drink and clothe them with what you yourselves eat, drink and wear, and do not burden them beyond their capacity; and if you give them a task beyond their capacity, then help them."
In Sahih Muslim this narration is reported through Ahmad bin Yunus, and in Bukhari through another route from al-A'mash.