Narrated by Abu Huraira:
The Prophet said, “Allah said, ‘I will be an opponent to three types of people on the Day of Resurrection: 1. One who makes a covenant in My Name, but proves treacherous; 2. One who sells a free person and eats his price; and 3. One who employs a laborer and takes full work from him but does not pay him for his lab our.’ “
[Bukhari Vol 3 Book 36 Hadith 470]