People will take refuge in the mountains to escape the Dajjal
عن أم شريك رضي الله عنها أنها سمعت النبى صلى الله عليه وسلم يقول : ليفرن الناس من الدجال فى الجبال ، قالت أم شريك رضي الله عنها : يا رسول الله ! فأين العرب يومئذ ؟ قال : هم قليل
It is narrated from Hazrat Umm Shareek (RA) that she heard the Prophet Muhammad (PBUH) say that people will hide in the mountains to escape the Dajjal. Umm Shareek (RA) said: O Messenger of Allah! Where will the Arabs be on that day? The Prophet (PBUH) replied that they will be very few on that day.
Reference: Muslim: Kitab al-Fitan: Chapter on the Remaining Hadiths of the Dajjal (2945) Ahmad (511/6) Tirmidhi (3930)