الاربعين النوويه

"14"

On the authority of Abdullah Ibn Masud (may Allah be pleased with him) who said: The Messenger of Allah (peace be upon him) said:

"It is not permissible to spill the blood of a Muslim except in three [instances]: the married person who commits adultery, a life for a life, and the one who forsakes his religion and separates from the community."

[Al-Bukhari & Muslim]