The blood of a Muslim man who testifies that there is no god but Allah and that I am the Messenger of Allah should not be lawfully shed but only for one of three reasons: married fornicator, soul for soul, and one who deserts his religion separating himself from the community.
Sunan Abi Dawud Book 40, Hadith 2
← Previous Hadith ‘Ali burned some people who retreated from Islam. When Ibn ‘Abbas was informed of it, he said: If it had been I, I would not have burned them, for the Messenger of Allah (ﷺ) said: Do not inflict Allah’s punishment on anyone, but would have had killed them on account of the statement of the Messenger of Allah (ﷺ). The Apostle said: Kill those who change their religion. When ‘Ali was informed about it he said: How truly Ibn ‘Abbas said!

Sunan Abi Dawud Book 40, Hadith 1 Next Hadith → The Messenger of Allah (ﷺ) Said: The blood of a Muslim man who testifies that there is no god but Allah and that Muhammad is Allah's Apostle should not lawfully be shed except only for one of three reasons: a man who committed fornication after marriage, in which case he should be stoned; one who goes forth to fight with Allah and His Apostle, in which case he should be killed or crucified or exiled from the land; or one who commits murder for which he is killed.

Sunan Abi Dawud Book 40, Hadith 3