Sayyiduna Abu Dharr (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Whoever of your slaves suits you, feed him from what you eat and clothe him from what you wear; and whoever of them does not suit you, sell him, and do not torment the creation of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النفقات / 15778