(4) باب إِذَا تَوَاجَهَ الْمُسْلِمَانِ بِسَيْفَيْهِمَا
Abu Huraira reported Allah's Messenger (ﷺ) many ahadith and one of them was this:
The last Hour will not come until the two parties (of Muslims) confront each other and there is a large-scale massacre amongst them and the claim of both of them is the same.
Reference: Sahih Muslim 157 h
In-book reference: Book 54, Hadith 22
USC-MSA web (English) reference(deprecated numbering scheme): Book 41, Hadith 6902