Hazrat Abdullah bin Mas'ud (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) said: The blood of a Muslim who professes the testimony "There is no god but Allah, Muhammad is the Messenger of Allah" is not lawful, except in three cases: a life for a life (in retaliation for murder), a married person who commits adultery, and one who leaves Islam (apostate) and abandons the community.