Imam Muslims narrates in his Sahih that the Prophet (peace and blessings of Allah upon him) said:
“Whosoever memorizes 10 verses from the beginning of Surah al-Kahf will be protected from the tribulation of the Dajjal.”
Imam Munawi in his Fayd al-Qadeer (commentary on Jami’ as-Saghir of Imam Suyuti) said:
“It is because of what is in the story of the people of the cave of wonders, such that whoever knows these will not be amazed by the Dajjal and therefore, he will not be tried; or, whosoever ponders over these verses and contemplates their meanings will be weary of the Dajjal and therefore safe from him; or that this is a specialty given to this Surah…”
And Allah knows best.