Sunan an-Nasa'i 4118
سنن النسائي#4118SahihIt was narrated from Abu Musa that:The Prophet [SAW] said: "If two Muslims confront each other with swords, and one kills the other, they will both be in Hell." It was 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
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 ZaiSahih
In-book reference: 37:153