Al-Kahf · 18:22

22. Some of those who delve into their incident will say about their number: They were three and their dog was the fourth amongst them. Others will say: They were five and their dog was the sixth amongst them. Both groups only said this as a guess without any proof. Some of them will say: They were seven and their dog was the eighth amongst them. Say, O Messenger: Your Lord knows best about their number. No one knows their number except for a few people whom Allah has informed about their number. So do not dispute with regard to their number or any other matter of theirs with the people of the scripture or with others except with an obvious argument and without delving into the matter, limiting it to the revelation that has come down to you with respect to them. Do not ask any of them about the details of their matter, because they do not know about it.