Jami` at-Tirmidhi 1402
جامع الترمذي#1402SahihNarrated 'Abdullah bin Mas'ud:that the Messenger of Allah (ﷺ) said: "The blood of a Muslim man, who testifies that none has the right to be worshipped Allah, is not lawful except for one of three cases: The (previously married or) married adulterer, a life for a life, and the one who leaves the religion and parts from the Jama'ah (the community of Muslims)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 16:18