The Black Banners from Khurassan
On the authority of Thawban, the Messenger of Allah (upon whom be blessings and peace) said:The Prophet Sallallahu ‘Alaihi Wa Sallam said: "Before your treasure, three will kill each other -- all of them are sons of a different caliph but none will be the recipient. Then the Black Banners will appear from the East and they will kill you in a way that has never before been done by a nation."
Thawban, a companion said: 'Then he said something that I do not remember by heart' then continued to say that the Prophet, praise and peace be upon him, said: "If you see him give him your allegiance, even if you have to crawl over ice, because surely he is the Caliph of Allah, the Mahdi. If you see the black (meaning war) flags coming from Khurasan (Afghanistan), join that army, even if you have to crawl over ice, for this is the army of the Caliph, the Mahdi and no one can stop that army until it reaches Jerusalem."
(Son of Majah, Al Busiri, Al Hakim, Ahmad Nuaym, Ad-Daylami, Hasan, son of Sufyaan, and Abu Nuaym.)
Related by Abu Hurayrah: The Prophet Sallallahu ‘Alaihi Wa Sallam said: "(Armies carrying) black flags will come from Khurasan (Afghanistan). No power will be able to stop them and they will finally reach Jerusalem where they will erect their flags." (Tirmidhi)
Subject: The Black Banners From Khurassan