Al-Kahf is the 18th chapter of the Quran with 110 verses. Regarding the timing and contextual background of the revelation, it is an earlier "Meccan surah", which means it was revealed in Mecca, instead of Medina.
Exegesis
Q18:9-26 "People of the Cave"
Verses 9–26 of the chapter retells the Christian folktale of the "People of the Cave". A few young believers lived in a time when they were tortured for their beliefs. Upon the guidance of God, they fled the city where believers were persecuted, together with their dog, and took refuge in a cave where they fell asleep. When they awoke they found that the people of the city had become believers.
Q18:27 No room for diversity
The commentary by Ozma Nasir Makarim Shirazi says, "There is no room for diversity to enter into His Words and Knowledge. His Speech and His Knowledge is not like the speech and knowledge of human beings which, as a result of a new invention or information, has to be changed". Ibn Kathir says this verse means of the words in the Quran, "no one can alter them, distort them or misinterpret them."
Q18:32-45 God destroys what He had given
In verses 32–44 the surah discusses a parable of two men, one of whom had been given blessings from God and the other poor. The rich one wronged his soul and started showing off with his wealth and noble lineage. Verse 36 explains that The rich man also told his companion that he doubted the existence of Judgment Day. At the end of the parable, God destroys what He had given the man. Q18:45Imam Musa al-Kadhim narrates in Kitab al-Kafi that Ali would bequeath his companions to view this world with the vision of an ascetic because it dislodges its residents. Ali provides them with the parable of a lush, green garden with scented dew that accumulates under the blades of grass but then gets separated from it in the morning, as Allah has said,
Finally, the surah mentions in verses 83–98 a man who traveled a great deal and reached the east and the west of the earth – namely, Dhul-Qarnayn. The Qur'an repeats the Syrian legend of a great king who helps a tribe of people build a massive wall of iron between two mountains. It goes on to say that this wall will be only destroyed on Judgement Day. The wall may have reflected a distant knowledge of the Great Wall of China, or of various Sassanid Persian walls built in the Caspian area against the northern barbarians, or a conflation of the two.
Circumstances of revelation
and hagiographer, Ibn Ishaq, reported in his traditional Muslimbiography of Muhammad, Sirat Rasul Allah that the 18th surah of the Qur'an was revealed to the Islamic prophetMuhammad by God on account of some questions posed by rabbis residing in the city of Medina – the verse was revealed during the Meccan period of Muhammad's life. According to Ibn Ishaq, Muhammad's tribe, the powerful Quraysh, were greatly concerned about their tribesman who had started claiming prophethood and wished to consult rabbis about the matter. The Quraysh sent two men to the rabbis of Medina, reasoning that they had superior knowledge of the scriptures and about the prophets of God. The two Quraysh men described their tribesman, Muhammad, to the rabbis. The rabbis told the men to ask Muhammad three questions: According to Ibn Ishaq, when Muhammad was informed of the three questions from the rabbis, he said that he would have the answers in the morning but did not say "if God wills it". For fifteen days, Muhammad waited eagerly for the revelation. Muhammad did not answer the question until then. Doubt in Muhammad began to grow amongst the people of Mecca. Then, after fifteen days, Muhammad received the revelation of al-Kahf as an answer to the questions.
Virtues
There is a hadith in Sahih Muslim that states that Muhammad said : "Whoever reads Sura Kahf on Friday, light shall shine forth for him between the two Fridays."
Common Muslim and Christian theme
The story of believers falling asleep in a cave for a long time is present also in the Christian tradition, see Seven Sleepers.
