Abu Huraira reported God’s messenger as saying, “Avoid the seven noxious things." When his hearers asked, “What are they, messenger of God?" he replied, “Associating anything with God, magic, killing one whom God has declared inviolate without a just cause, devouring usury, consuming the property of an orphan, turning back when the army advances, and slandering chaste women who are believers but indiscreet."
(Bukhari and Muslim.)