What are the rights of a concubine in Islam?

The rights of a slave woman (jariya) in Islam are summarized as being treated kindly and not being burdened with what she cannot bear, as stated in the Prophet's (peace be upon him) advice: "Prayer and what your right hands possess," and in his saying: "They are your brothers, your servants whom Allah has placed under your hands. So, whoever has his brother under his hand, let him feed him from what he eats, and clothe him from what he clothes himself with, and do not burden them with what overwhelms them. If you do burden them, then assist them." The command to treat slave women kindly is also mentioned in the hadith: "A man who had a slave woman whom he nourished well and educated well, then freed her and married her, will have two rewards."