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It was reported that the Messenger of Allah (ﷺ) ﷺ said, “Whoever reads Sūrat al-Kahf on the night of Jumu’ah, a light will shine for him which extends from him to the Ancient House (i.e., the Kaʿbah).” Reference: Sunan al-Darimi 3312; Sunan Al-Bayhaqi 5856; Sahīh al-Targhīb wa at-Tarhīb 736. Note: Jumu’ah is not equivalent to Friday, rather it begins at Maghrib/sunset of Thursday and ends as the maghrib/sunset time comes in on Friday.
Source: sunnah.com
Other translations
Arabic
عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ ، قَالَ :" مَنْ قَرَأَ سُورَةَ الْكَهْفِ لَيْلَةَ الْجُمُعَةِ، أَضَاءَ لَهُ مِنْ النُّورِ فِيمَا بَيْنَهُ وَبَيْنَ الْبَيْتِ الْعَتِيقِ ".
sunnah.com