Tafsir Al-Jalalayn: Al-Kahf, Ayah 22

They will say that is some of those disputing the number of the youths of the cave at the time of the Prophet s in other words some of these will say that they the youths were ‘Three; their dog the fourth of them’; and they some others among them will say ‘Five; their dog the sixth of them’ — both of these sayings were those of the Christians of Najrān — guessing at random in other words out of supposition not having been present with them at the time and this statement ‘guessing at random’ refers back to both sayings and is in the accusative because it is an object denoting reason in other words they said this for the reason that they were merely supposing it. And they that is the believers will say ‘Seven; and their dog the eighth of them’ the sentence is part of the subject clause the predicate of which is the adjectival qualification of sab‘a ‘seven’ namely thāminuhum ‘the eighth of them’ with the additional wāw wa-thāminuhum which is said to be for emphasis or an indication that the adjective is semantically attached to that which it is qualifying. The qualification of the first two sayings as being ‘random’ but not the third is proof that the latter is the satisfactory and correct number. Say ‘My Lord knows best their number and none knows them except a few’ Ibn ‘Abbās said ‘I am one of these “few” described’ and he mentioned that they were seven. So do not contend concerning them except with an outward manner of contention except with that which has been revealed to you and do not question concerning them do not ask for opinions from any of them from the People of the Scripture the Jews. The people of Mecca asked him the Prophet about the story of the People of the Cave and so he said to them ‘I will tell you about it tomorrow’ but without adding the words ‘If God wills’ inshā’a’ Llāhu and so the following was revealed