Sahih Muslim
The Book Pertaining to the Turmoil and Portents of the Last Hour (Kitab Al-Fitan wa Ashrat As-Saah)
Book Number: 041 / Hadith Number: 6988
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: The Last Hour would not come until there would arise about thirty impostors, liars, and each one of them would claim that he is a messenger of Allah.