‏الأيمان : Hadeeth No:4095 Abu Huraira reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: It is essential to feed the slave, clothe him (properly) and not burden him with work which is beyond his power....

‏الزهد والرقائق‏ : Hadeeth No:7123 Abu Wa'il reported: I was in the company of Usama b. Zaid that a person said: What prevents you to visit Uthman and talk to him for what he does? The rest of the hadith is the same....