Abud-Darda’ (رضي الله عنه) reported: The Messenger of Allah (salallahu ‘alayhi wa sallam) said: “Whoever commits to memory the first ten Ayat of the Surat Al-Kahf, will be protected from (the trial of) Ad-Dajjal (Antichrist).”[Muslim]
In another narration, the Messenger of Allah (salallahu ‘alayhi wa sallam) said: “(Whoever commits to memory) the last ten Ayat of Surat Al-Kahf, he will be protected from (the trial of) Ad-Dajjal (Antichrist).”
Ad-Dajjal will appear sometime before Yaum-ul-Qiyamah. Allah, the Almighty will give him some supernatural powers the manifestation of which will shake the faith of many people. For this reason, this will be a serious trial. All Prophets (alayhimus-sallam) warned their people against him. Our Prophet (salallahu ‘alayhi wa sallam) also warned us against him and ordered us to guard ourselves from it and strictly advised us to seek Refuge of Allah against it.
It was narrated that Ibn ‘Umar (رضي الله عنهما) said: “The Messenger of Allaah (salallahu ‘alayhi wa sallam) said:‘Whoever reads Soorat al-Kahf on the day of Jumu’ah (Friday), a light will shine for him from beneath his feet to the clouds of the sky, which will shine for him on the Day of Resurrection, and he will be forgiven (his sins) between the two Fridays.'” [Al-Mundhiri رحمة اللہ علیه said, this was narrated by Abu Bakr ibn Mardawayh رحمة اللہ علیه in his Tafseer, with an isnaad with which there was nothing wrong]
From Abu Sa’eed al-Khudri (رضي الله عنه), who said: “Whoever reads Soorat al-Kahf on the night of Jumu’ah (Friday), will have a light that will stretch between him and the Ancient House (the Ka’bah).” [Narrated by al-Daarimi, 3407]
“Whoever reads Soorat al-Kahf on the day of Jumu’ah (Friday), will have a light that will shine from him from one Friday to the next.” [Narrated by al-Haakim, 2/399; al-Bayhaqi, 3/249. Ibn Hajar said in Takhreej al-Adhkaar that this is a hasan hadeeth, and he said, this is the strongest report that has been narrated concerning reading Soorat al-Kahf. See: Fayd al-Qadeer, 6/198]
The soorah may be read during the night or the day of Jumu’ah. The night of Jumu’ah starts from sunset on Thursday, and the day of Jumu’ah ends at sunset. Therefore the time for reading this soorah extends from sunset on Thursday to sunset on Friday.
Al-Mannaawi رحمة اللہ علیه said: Al-Haafiz ibn Hajar رحمة اللہ علیه said in his Amaali: “In some reports it says ‘the day of Jumu’ah’ and in some reports it says ‘the night of Jumu’ah’. They may be reconciled by saying that what is meant is the day which includes the night and vice versa.” (Fayd al-Qadeer, 6/199)
Source: Mufti says.