Narrated Hudhaifa bin Al-Yaman:

The people used to ask Allah's Apostle 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 Apostle! 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."

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، حَدَّثَنَا ابْنُ جَابِرٍ، حَدَّثَنِي بُسْرُ بْنُ عُبَيْدِ اللَّهِ الْحَضْرَمِيُّ، أَنَّهُ سَمِعَ أَبَا إِدْرِيسَ الْخَوْلاَنِيَّ، أَنَّهُ سَمِعَ حُذَيْفَةَ بْنَ الْيَمَانِ، يَقُولُ كَانَ النَّاسُ يَسْأَلُونَ رَسُولَ اللَّهِ ﷺ عَنِ الْخَيْرِ، وَكُنْتُ أَسْأَلُهُ عَنِ الشَّرِّ، مَخَافَةَ أَنْ يُدْرِكَنِي فَقُلْتُ يَا رَسُولَ اللَّهِ إِنَّا كُنَّا فِي جَاهِلِيَّةٍ وَشَرٍّ فَجَاءَنَا اللَّهُ بِهَذَا الْخَيْرِ، فَهَلْ بَعْدَ هَذَا الْخَيْرِ مِنْ شَرٍّ قَالَ " نَعَمْ ". قُلْتُ وَهَلْ بَعْدَ ذَلِكَ الشَّرِّ مِنْ خَيْرٍ قَالَ " نَعَمْ، وَفِيهِ دَخَنٌ ". قُلْتُ وَمَا دَخَنُهُ قَالَ " قَوْمٌ يَهْدُونَ بِغَيْرِ هَدْىٍ، تَعْرِفُ مِنْهُمْ وَتُنْكِرُ ". قُلْتُ فَهَلْ بَعْدَ ذَلِكَ الْخَيْرِ مِنْ شَرٍّ قَالَ " نَعَمْ، دُعَاةٌ عَلَى أَبْوَابِ جَهَنَّمَ، مَنْ أَجَابَهُمْ إِلَيْهَا قَذَفُوهُ فِيهَا ". قُلْتُ يَا رَسُولَ اللَّهِ صِفْهُمْ لَنَا. قَالَ " هُمْ مِنْ جِلْدَتِنَا، وَيَتَكَلَّمُونَ بِأَلْسِنَتِنَا ". قُلْتُ فَمَا تَأْمُرُنِي إِنْ أَدْرَكَنِي ذَلِكَ قَالَ " تَلْزَمُ جَمَاعَةَ الْمُسْلِمِينَ وَإِمَامَهُمْ ". قُلْتُ فَإِنْ لَمْ يَكُنْ لَهُمْ جَمَاعَةٌ وَلاَ إِمَامٌ قَالَ " فَاعْتَزِلْ تِلْكَ الْفِرَقَ كُلَّهَا، وَلَوْ أَنْ تَعَضَّ بِأَصْلِ شَجَرَةٍ، حَتَّى يُدْرِكَكَ الْمَوْتُ، وَأَنْتَ عَلَى ذَلِكَ ".