Imam Ahmad narrated from Abu Ad-Darda’ (may Allah be pleased with him) that the Prophet ﷺ said:
“Whoever memorizes ten verses from the beginning of Surah Al-Kahf will be protected from the Dajjal.”
Regarding the narration reported by At-Tirmidhi:
“Whoever memorizes three verses from the beginning of Surah Al-Kahf.”
He classified it as Hasan Sahih.
In his Al-Mustadrak, Al-Hakim narrated from Abu Sa‘id (may Allah be pleased with him) that the Prophet ﷺ said:
“Whoever recites Surah Al-Kahf on Friday will be illuminated with a light from one Friday to the next.”
Then he said:
“This hadith has an authentic (Sahih) chain of narration, although Al-Bukhari and Muslim did not record it.”
Al-Hafiz Abu Bakr Al-Bayhaqi also recorded this narration in his Sunan through Al-Hakim. He then narrated, with his chain of transmission, that the Prophet ﷺ said:
“Whoever recites Surah Al-Kahf as it was revealed, it will be a light for him on the Day of Resurrection.”