Sahih Muslim , Book 41, Hadith 6949 (USC-MSA) ⓘ
Abu Huraira reported Allah's Messenger as saying: By Him in Whose Hand is my life, a time would come when the murderer would not know why he has committed the murder, and the victim would not know why he has been killed.
وَحَدَّثَنَا ابْنُ أَبِي عُمَرَ الْمَكِّيُّ، حَدَّثَنَا مَرْوَانُ، عَنْ يَزِيدَ، - وَهُوَ ابْنُ كَيْسَانَ - عَنْ أَبِي حَازِمٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " وَالَّذِي نَفْسِي بِيَدِهِ لَيَأْتِيَنَّ عَلَى النَّاسِ زَمَانٌ لاَ يَدْرِي الْقَاتِلُ فِي أَىِّ شَىْءٍ قَتَلَ وَلاَ يَدْرِي الْمَقْتُولُ عَلَى أَىِّ شَىْءٍ قُتِلَ " .
also referenced under: Book 54, Hadith 69 (In-Book) & Hadith 2908 (Reference)