Sayyiduna Hudhayfah bin al-Yaman (may Allah be pleased with him) said: People used to ask the Messenger of Allah (peace and blessings be upon him) about good, and I used to ask him about evil for fear that it would overtake me. I said: O Messenger of Allah, we were in ignorance (jahiliyyah) and evil, then Allah brought us this good; will there be evil after this good? He said: "Yes." I said: Will there be good after that evil? He said: "Yes, and in it there will be some haze (dakhan)." I said: What is its haze? He said: "People who follow a way other than my Sunnah and guide by other than my guidance; you will approve of some of what they do and disapprove of some." I said: Will there be evil after that good? He said: "Yes, callers at the gates of Hell; whoever answers them, they will throw him into it." I said: O Messenger of Allah, describe them to us. He said: "Yes, they are of our own skin and speak our tongues." I said: O Messenger of Allah, what do you command me if that overtakes me? He said: "Hold fast to the community (jama'ah) of the Muslims and their imam." I said: And if they have neither a community nor an imam? He said: "Then keep away from all those sects, even if you have to bite on the root of a tree, until death comes to you while you are in that state."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16795