On the authority of Abu Hurayrah (may Allah be pleased with him), who said that the Messenger of Allah (peace be upon him) said that Allah the Almighty said: There are three (1) whose adversary I shall be on the Day of Resurrection: a man who has given his word by Me and has broken it; a man who has sold a free man (2) and has consumed the price; and a man who has hired a workman, has exacted his due in full from him and has not given him his wage. i.e. types of men. i.e. a man who has made a slave of another and has sold him.

[al-Bukhari]