Narrated Hudhaifa bin Al-Yaman:

The people used to ask Allah's Messenger (ﷺ) about the good but I used to ask him about the evil lest I should be overtaken by them. So I said, "O Allah's Messenger (ﷺ)! We were living in ignorance and in an (extremely) worst atmosphere, then Allah brought to us this good (i.e., Islam); will there be any evil after this good?" He said, "Yes." I said, 'Will there be any good after that evil?" He replied, "Yes, but it will be tainted (not pure.)'' I asked, "What will be its taint?" He replied, "(There will be) some people who will guide others not according to my tradition? You will approve of some of their deeds and disapprove of some others." I asked, "Will there be any evil after that good?" He replied, "Yes, (there will be) some people calling at the gates of the (Hell) Fire, and whoever will respond to their call, will be thrown by them into the (Hell) Fire." I said, "O Allah s Apostle! Will you describe them to us?" He said, "They will be from our own people and will speak our language." I said, "What do you order me to do if such a state should take place in my life?" He said, "Stick to the group of Muslims and their Imam (ruler)." I said, "If there is neither a group of Muslims nor an Imam (ruler)?" He said, "Then turn away from all those sects even if you were to bite (eat) the roots of a tree till death overtakes you while you are in that state."