Hadeeth Qudsi 21:

On the authority of AbuHurayrah (may Allah be pleased with him), who said that the Messengerof Allah  said that Allah the Almighty said:

There are three (1) whoseadversary I shall be on the Day of Resurrection: a man who has givenhis word by Me and has broken it; a man who has sold a free man (2) andhas consumed the price; and a man who has hired a workman, has exactedhis 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.

It was related by al-Bukhari(also by Ibn Majah and Ahmad ibn Hanbal).