Verse 18

وَتَحْسَبُهُمْ أَيْقَاظًا وَهُمْ رُقُودٌ وَنُقَلِّبُهُمْ ذَاتَ ٱلْيَمِينِ وَذَاتَ ٱلشِّمَالِ وَكَلْبُهُم بَـٰسِطٌ ذِرَاعَيْهِ بِٱلْوَصِيدِ لَوِ ٱطَّلَعْتَ عَلَيْهِمْ لَوَلَّيْتَ مِنْهُمْ فِرَارًا وَلَمُلِئْتَ مِنْهُمْ رُعْبًا

And you would think that they were awake while in fact they were asleep. And We turned them to the right and the left as their dog stretched his two arms in the cave. Had you come across them you would have run away as you would have been terrified by them.