Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 178
Narrated 'Amr bin Taghlib:
The Prophet said, "One of the portents of the Hour is that you will fight with people wearing shoes made of hair; and one of the portents of the Hour is that you will fight with broad-faced people whose faces will look like shields coated with leather."