It is narrated from Hazrat Abu Dharr (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Your slaves are your brothers whom Allah has placed under your authority as a trial. Therefore, whoever has his brother under his authority should feed him from what he eats, clothe him from what he wears, and should not assign him a task that overpowers him. If such a task is assigned, then he should help him with it himself."
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 21409