Surah Al-Kahf Verse 11

2339 Drew (a veil) over their ears: i.e., sealed their ears so that they heard nothing. As they were in the Cave they saw nothing. So they were completely cut off from the outer world. It was as if they had died, with their knowledge and ideas remaining at the point of time when they entered the Cave. It is as if watch stops at the exact moment of some accident, and any one taking it up afterwards can precisely fix the time of the accidents.