There are saheeh ahaadeeth from the Prophet (peace and blessings of Allaah be upon him) concerning the virtues of reciting Soorat al-Kahf during the day or night of Jumu’ah (Friday). These include:
From Abu Sa’eed al-Khudri, who said: “Whoever reads Soorat al-Kahf on the night of Jumu’ah, will have a light that will stretch between him and the Ancient House (the Ka’bah).” (Narrated by al-Daarimi, 3407. This hadeeth was classed as saheeh by Shaykh al-Albaani in Saheeh al-Jaami, 6471)
“Whoever reads Soorat al-Kahf on the day of Jumu’ah, 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. It was classed as saheeh by Shaykh al-Albaani in Saheeh al-Jaami’, 6470)
It was narrated that Ibn ‘Umar (may Allaah be pleased with him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Whoever reads Soorat al-Kahf on the day of Jumu’ah, 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.’”
Read Surat Al-Kahf here with translation/transliteration
Shaykh Saalih Ibn Fawzaan Ibn `Abdullaah al-Fawzaan (حفظه الله ) - in the Chapter of Ahkaam Salaat al-Jumu`ah (The Rulings of Salaat al-Jumu`ah), he said:
…….ومن خصائص يوم الجمعة قراءة سورة الكهف في يومها؛ فقد ثبت عن النبي صلى الله عليه وسلم
من قرأ سورة الكهف يوم الجمعة؛ سطَع له نور من تحت قدمه إلى عنان السماء، يضيء به يوم القيامة، وغفر له ما بين الجمعتين رواه الحاكم والبيهقي
“And from the specific virtues of Jumu`ah is, the recitation of Surah al-Kahf during its day. For it has been confirmed from the Prophet that he ﷺ said:
‘Whoever recites Surah al-Kahf on the Day of Jumu`ah, a light will come forth from beneath his feet to the clouds of the sky, and which will shine for him on the Day of Judgment, and all his (minor) sins between the 2 Fridays will be forgiven.”[Recorded by al-Haakim and al-Bayhaqi.]
Surah al-Kahf | Protection from Dajjal (notes from Ustadh Yasir Qadhi's intro)
Surah al-Kahf is full of stories and those stories are of trials, and the main theme is that Allah will protect you against all trials. The story of Ahl al-Kahf is about the trial of religion, where the young men flee to the cave in order to remain safe from the ruler who is after them for being believers. Then there is the story of the two men who own a garden, and it is about the trial of property. The story of Musa and Khidr (peace be upon them) is about the trial of knowledge, and the story of Dhul Qarnain (peace be upon him) is about the trial of power & authority.
Abu Darda (may Allah be pleased with him) narrates from the Prophet ﷺ that whoever memorizes the first ten verses of Surah al-Kahf will be secure from the Dajjal. In another long hadith where the Prophet ﷺ describes to his companions the Dajjal and his emergence, he tells them that if any of them were to see him, he should recite the first ten verses of Surah al-Kahf.
With the emergence of the Dajjal will appear trials. Those who do not accept Dajjal as their king will go through trials as Allah will give Dajjal the power of giving and depriving. How perfectly the tenth verse finishes; our Lord, bestow your mercy upon us and help us in our affairs. That is exactly where the tenth verse stops and it is an optimistic verse. Notice here, what is the eleventh verse, which is not what we are supposed to read when we meet the Dajjal (the Anti-Christ) - Allah saved them (ahl al-Kahf) by causing them to go to sleep. We don’t want to be saved through sleep. The Prophet ﷺ told us we will be saved when ‘Isa ibn Maryam (peace be upon him) comes. Our saving from Dajjal will not be through sleep, so we don’t recite the eleventh verse but stop exactly on the tenth.