Sahih Bukhari | Volume 8 | Hadith Number 840

Narrated by Abu Huraira
The Prophet said, "Avoid the seven great destructive sins." They (the people!) asked, "O Allah's Apostle! What are they?" He said, "To join partners in worship with Allah; to practice sorcery; to kill the life which Allah has forbidden except for a just cause (according to Islamic law); to eat up usury (Riba), to eat up the property of an orphan; to give one's back to the enemy and freeing from the battle-field at the time of fighting and to accuse chaste women who never even think of anything touching chastity and are good believers."