Sahih al-Bukhari — Virtues and Merits of the Prophet (pbuh) and his Companions — Hadith No: 3606
Translation
Narrated Hudhaifa bin Al-Yaman:The people used to ask Allah's Messenger (ﷺ) about good, but I used to ask him about evil for fear that it might overtake me. Once I said, "O Allah's Messenger (ﷺ)! We were in ignorance and in evil and Allah has bestowed upon us the present good; will there be any evil after this good?" He said, "Yes." I asked, "Will there be good after that evil?" He said, "Yes, but it would be tained with Dakhan (i.e. Little evil)." I asked, "What will its Dakhan be?" He said, "There will be some people who will lead (people) according to principles other than my tradition. You will see their actions and disapprove of them." I said, "Will there be any evil after that good?" He said, "Yes, there will be some people who will invite others to the doors of Hell, and whoever accepts their invitation to it will be thrown in it (by them)." I said, "O Allah's Messenger (ﷺ)! Describe those people to us." He said, "They will belong to us and speak our language" I asked, "What do you order me to do if such a thing should take place in my life?" He said, "Adhere to the group of Muslims and their Chief." I asked, "If there is neither a group (of Muslims) nor a chief (what shall I do)?" He said, "Keep away from all those different sects, even if you had to bite (i.e. eat) the root of a tree, till you meet Allah while you are still in that state