Sunan Ibn Majah, Chapter: The Chapters on Tribulations

"Shall I not tell you a Hadith that I heard from the Messenger of Allah (saw), which no one will tell you after me? I heard it from him (saying): 'Among the portents of the Hour are that knowledge will be taken away and ignorance will prevail, illegal sex will become widespread and wine will be drunk, and men will disappear and women will be left, until there is one man in charge of fifty women."