Sunan an Nasai
4124
Sahih+2

It was narrated from Abu Musa Al-Ash'ari that :The Messenger of Allah [SAW] said: "If two Muslims confront each other with swords and one of them kills the other, then the killer and the slain will both be in Hell." A man said: "O Messenger of Allah, (we understand about) the killer, but what about the one who is killed?" He said: "He wanted to kill his companion

SahihAbu Ghuddah
SahihAl-Albani