From Sahih Bukhari (Hadith 3609):
Narrated Abu Huraira:The Prophet (ﷺ) said, "The Hour will not be established till there is a war between two groups among whom there will be a great number of casualties, though the claims (or religion) of both of them will be one and the same. And the Hour will not be established till there appear about thirty liars, all of whom will be claiming to be the messengers of Allah
Reference: Bukhari 3609