Virtues and Merits of the Prophet (pbuh) and his Companions

Bukhari :: Book 4 :: Volume 56 :: Hadith 806

Narrated Abu Huraira:

The Prophet 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. "