Hudhayfah ibn al-Yaman said, "People used to ask the Prophet - sallallâhu ’alayhi wa sallam - about good things, but I used to ask him about bad things because I was afraid that they might overtake me. I said, 'O Messenger of Allâh, we were lost in ignorance (Jahiliyyah) and evil, then Allâh brought this good (i.e. Islâm). Will some evil come after this good thing?' He said,'Yes' I asked, 'And will some good come after that evil?' He said, 'Yes, but it will be tainted with some evil' I asked, 'How will it be tainted?' He said, 'There will be some people who will lead others on a path different from mine. You will see good and bad in them." I asked, 'Will some evil come after that good?' He said, 'Some people will be standing and calling at the gates of Hell; whoever responds to their call, they will throw him into the Fire.' I said, 'O Messenger of Allâh, describe them for us.' He said, 'They will be from our own people, and will speak our language.' I asked, 'What do you advise me to do if I should live to see that?' He said, 'Stick to the main body (jama'ah) of the Muslims and their leader (Imâm). I asked, What if there is no main body and no leader?' He said 'Isolate yourself from all of these sects, even if you have to eat the roots of trees until death overcomes you while you are in that state.'"
'Abdullâh ibn Mas'ud said: "The Prophet said, 'Islâm began as something strange, and it will revert to being strange as it was in the beginning, so good tidings for the strangers.' Someone asked, 'Who are the strangers?' He said, 'The ones who break away from their people (literally, 'tribes') for the sake of Islâm.' "
This Hadîth was narrated by Ibn Majah on the authority of Anas and Abû Hurayrah.
