The Messenger of Allah ﷺ said, "The blood of a Muslim who testifies that there is no god but Allah and that I am the Messenger of Allah is not lawful to shed except in one of three cases: a life for a life, a married person who commits adultery, and one who abandons his religion and forsakes the community."
قال رسول الله ﷺ: ((لا يحل دم امرئ مسلم يشهد أن لا إله إلا الله وأني رسول الله إلا بإحدى ثلاث: النفس بالنفس، والثيب الزاني، والمفارق لدينه التارك للجماعة)).
Bukhari narrated it in the Book of Diyat (6878), and Muslim narrated it in the Book of Qasama (1676), both through Amash, from Abdullah bin Mura, from Masruq, from Abdullah bin Masud, who related it.