(2) باب قَوْلِ اللَّهِ تَعَالَى {وَمَنْ أَحْيَاهَا}
Narrated Al-Ahnaf bin Qais:
I went to help that man (i.e., `Ali), and on the way I met Abu Bakra who asked me, "Where are you going?" I replied, "I am going to help that man." He said, "Go back, for I heard Allah's Messenger (ﷺ) saying, 'If two Muslims meet each other with their swords then (both) the killer and the killed one are in the (Hell) Fire.' I said, 'O Allah's Messenger (ﷺ)! It is alright for the killer, but what about the killed one?' He said, 'The killed one was eager to kill his opponent."
Reference: Sahih al-Bukhari 6875
In-book reference: Book 87, Hadith 14
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 9, Book 83, Hadith 14