Chapter 18, Verse 22, The cave
سورة الكهف
سَيَقُولُونَ ثَلَٰثَةٞ رَّابِعُهُمۡ كَلۡبُهُمۡ وَيَقُولُونَ خَمۡسَةٞ سَادِسُهُمۡ كَلۡبُهُمۡ رَجۡمَۢا بِٱلۡغَيۡبِۖ وَيَقُولُونَ سَبۡعَةٞ وَثَامِنُهُمۡ كَلۡبُهُمۡۚ قُل رَّبِّيٓ أَعۡلَمُ بِعِدَّتِهِم مَّا يَعۡلَمُهُمۡ إِلَّا قَلِيلٞۗ فَلَا تُمَارِ فِيهِمۡ إِلَّا مِرَآءٗ ظَٰهِرٗا وَلَا تَسۡتَفۡتِ فِيهِم مِّنۡهُمۡ أَحَدٗا
(Some) say they were three, the dog being the fourth among them; (others) say they were five, the dog being the sixth, guessing at the unseen; (yet others) say they were seven, the dog being the eighth. Say (O Muhammad ﷺ): "My Lord knows best their number; none knows them but a few." So debate not (about their number, etc.) except with the clear proof (which We have revealed to you). And consult not any of them (people of the Scripture, Jews and Christians) about (the affair of) the people of the cave.