While we were sitting with the Prophet (SAWA), a group of young men passed by us and the face of the Prophet turned pale. We asked, ?O Messenger of Allah! We see a look of dislike on your face.' He said, 'We are members of a household for whom Allah has chosen the Hereafter over this world. And this household of mine will be afflicted by banishment and exile after my demise, until a people will emerge from these parts and he pointed to the East with black flags. They will repeatedly demand what is right and will be denied it, so they will fight steadfastly until they are given what they demand. But they will not accept it for themselves, until they give it to a man from my posterity who will fill [the world] with fairness and justice as it was filled with oppression and injustice before. Whoever lives to know them should join them even if he has to crawl on snow.'