Hadithcore
Sahih Muslim, 2908 b
sahih

Abu Huraira reported Allah's Messenger (ﷺ) as saying:

The world would not come to an end until a day would come to the people on which the murderer would not know as to why he has killed and the slain would not know as to why he has been murdered. It would be said: Why would It happen? To which he replied: It would be because of general massacre and bloodshed. And the slaughterers and the slain would be in Fire, and in the narration of Ibn Aban, the name of Abu Isma'il has been mentioned.

وَحَدَّثَنَا عَبْدُ اللَّهِ بْنُ عُمَرَ بْنِ أَبَانَ، وَوَاصِلُ بْنُ عَبْدِ الأَعْلَى، قَالاَ حَدَّثَنَا مُحَمَّدُ، بْنُ فُضَيْلٍ عَنْ أَبِي إِسْمَاعِيلَ الأَسْلَمِيِّ، عَنْ أَبِي حَازِمٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ وَالَّذِي نَفْسِي بِيَدِهِ لاَ تَذْهَبُ الدُّنْيَا حَتَّى يَأْتِيَ عَلَى النَّاسِ يَوْمٌ لاَ يَدْرِي الْقَاتِلُ فِيمَ قَتَلَ وَلاَ الْمَقْتُولُ فِيمَ قُتِلَ ‏"‏ ‏.‏ فَقِيلَ كَيْفَ يَكُونُ ذَلِكَ قَالَ ‏"‏ الْهَرْجُ ‏.‏ الْقَاتِلُ وَالْمَقْتُولُ فِي النَّارِ ‏"‏ ‏.‏ وَفِي رِوَايَةِ ابْنِ أَبَانَ قَالَ هُوَ يَزِيدُ بْنُ كَيْسَانَ عَنْ أَبِي إِسْمَاعِيلَ ‏.‏ لَمْ يَذْكُرِ الأَسْلَمِيَّ ‏.‏

References2 variants
In-Book Reference
Book 54, Hadith 70
USC-MSA web (English) reference
Book 41, Hadith 6950 (deprecated numbering scheme)