Ibn Sirin محمد بن سيرين الأنصاري · The Book of Fighting [The Prohibition of Bloodshed]

The Prophet said: "If two Muslims confront each other with swords, each of them wanting to kill the other, they will both be in Hell." It was said to him: "O Messenger of Allah, (we understand about) the killer, but what about the one who is killed?" He said: "He was determined to kill his companion."