Sahih Muslim 2908aBook 54, Hadith 69
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 " .
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.