Overall meaning : Allah Almighty reveals another scene portraying the conditions of these youths: Just as We caused them to sleep for so many years and then awakened them from their sleep, so too We made their story known to the people of the city—that was when people at that time disputed the reality of resurrection after death, with some believing in it while other denying it—so that they might know that Allah’s promise of resurrection is true and that there is no doubt about the Day of Judgement.
After the youths’ death, those whom Allah had made stumble upon them said, ‘Wall up the mouth of the cave to hide them; their Lord knows best about them.’ Those who had authority over people’s affairs, said, ‘We will build a place of worship over them in their memory.’
Then, relating the disagreement that has arisen over the number of these youths, Allah says: Some of those who speculate about their number say that they were three, their dog being the fourth. Some others say that they were five, heir dog being the sixth, both guessing at random, without any evidence whatsoever. And yet others say that they were seven, their dog being the eighth.
Say, Muhammad, to those who argue about their number without knowledge: ‘My Lord knows best how many they were. Only a few know their exact number.’ Therefore, when you dispute about them, adhere only to that is clearly known and do not ask anyone among the People of the Book concerning their number and circumstances, for they do not know.
Then, enjoining His Prophet, may Allah bless him and grant him peace, not to say he is definitely going to do something in the future unless he attaches his intention to Allah’s will, He says: Never say of something that you intend to do, ‘I will do it tomorrow,’ without adding the phrase ‘in shaa Allaah (Allah willing).’ Remember your Lord by saying this if you forget to do so, and pray saying, ‘I pray that my Lord will guide me and show me the closest paths leading to what is right.’
The Almighty, who knows all things, then reveals the length of the youths’ stay in the cave: They slept in their cave for three hundred and nine years. Say, Muhammad: Allah knows best how long they remained in the cave. To Him are the secrets of the heavens and the earth known. How perfectly He sees all creation, and how perfectly He hears all sounds! All creatures have no one other than Him to manage and take care of their affairs, nor does He share His rule and decision with anyone whatsoever.