What he said about the one who was killed
They asked the obvious question about the second man.
إِذَا الْتَقَى الْمُسْلِمَانِ بِسَيْفَيْهِمَا فَالْقَاتِلُ وَالْمَقْتُولُ فِي النَّارِ
Idhā-ltaqā-l-muslimāni bi-sayfayhimā fa-l-qātilu wa-l-maqtūlu fi-n-nār
When two Muslims meet with their swords, the killer and the killed are both in the Fire.
Where this comes from
They said: this is the killer, but what about the one who was killed. He said: he was intent on killing his companion. What is being judged is what was in the hand and the intention behind it, not who happened to be faster.
The full narration
Narrated Al-Ahnaf bin Qais: While I was going to help this man ('Ali Ibn Abi Talib), Abu Bakra met me and asked, "Where are you going?" I replied, "I am going to help that person." He said, "Go back for I have heard Allah's Messenger (ﷺ) saying, 'When two Muslims fight (meet) each other with their swords, both the murderer as well as the murdered will go to the Hell-fire.' I said, 'O Allah's Messenger (ﷺ)! It is all right for the murderer but what about the murdered one?' Allah's Messenger (ﷺ) replied, "He surely had the intention to kill his companion
Source
Ṣaḥīḥ al-Bukhārī · 31
- Agreed upon as authentic (al-Bukhārī / Muslim)