سورة Al-Kahf ( The Cave ) - الآية 22

Some will say: 'They were three; their dog was the fourth' Others, guessing at the Unseen, will say: 'They were five and their dog was the sixth' And yet others: 'Seven; their dog was the eighth' Say: 'My Lord knows best their number. Except for a few none know their number' Therefore, do not dispute with them except in outward disputation, and do not ask any of them concerning them.