Sunan an-Nasa'i 4721
سنن النسائي#4721SahihIt was narrated from 'Abdullah that the Messenger of Allah said:"It is not permissible to shed the blood of a Muslim except in one of three cases: A soul for a soul, a adulterer who has been married, and one who separates leaving his religion
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 45:16