I came out with the intention of (participating in) fighting. Abu Bakrah met me and said: Go back, for I heard the Messenger of Allah ﷺ say: When two Muslims face each other with their swords, the killer and the slain will go to Hell. He asked: Messenger of Allah, this is the killer (so naturally he should go to Hell), but what is the matter with the slain ? He replied: He intended to kill his companion.  

خَرَجْتُ وَأَنَا أُرِيدُ يَعْنِي فِي الْقِتَالِ فَلَقِيَنِي أَبُو بَكْرَةَ فَقَالَ ارْجِعْ فَإِنِّي سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ إِذَا تَوَاجَهَ الْمُسْلِمَانِ بِسَيْفَيْهِمَا فَالْقَاتِلُ وَالْمَقْتُولُ فِي النَّارِ قَالَ يَا رَسُولَ اللَّهِ هَذَا الْقَاتِلُ فَمَا بَالُ الْمَقْتُولِ قَالَ إِنَّهُ أَرَادَ قَتْلَ صَاحِبِهِ  

The tradition mentioned above has also been transmitted briefly by al-Hasan through a different chain of narrators to the same effect.  

يُقَالُ لَهُ الْحُسَيْنُ