I heard the Messenger of Allah say, "Every sin may be forgiven by Allah except for a man who kills a believer intentionally, or a man who dies as a disbeliever."
سمعت رسول الله يقول: كل ذنب عسى الله أن يغفره إلا الرجل يقتل المؤمن متعمدا، أو الرجل يموت كافرا.
Nasai (3984), Ahmad (16907), and Ibn Abu Asim in al-Diyat (27) narrated it, and Hakim graded it sahih (4/351). All of them narrated it from the hadith of Safwan bin Isa, from Thawr, from Abu Awn, from Abu Idris, who said, "I heard Muawiya delivering a sermon" - and he spoke little - he said, "I heard him delivering a sermon, saying, 'I heard the Messenger of Allah ﷺ saying,'" then he mentioned the hadith.Its chain is hasan because of Abu Awn, who is Ansari, Shami, the one-eyed, for his hadith is hasan. A number of scholars narrated from him, and Ibn Hibban and Ajli deemed him trustworthy. Ibn Abu Asim said, "This is a hasan and radiant chain."As for his statement, "The man is killed," the apparent meaning of this hadith agrees with the Quran, and more than one of the early generations held this view. But the majority hold that it should be understood as a severe warning, in light of the words of Allah Almighty,"Indeed, Allah does not forgive associating partners with Him, but He forgives whatever is less than that for whom He wills" [Nisa 4:116]