Surah Al-Kahf 18:11

فَضَرَبْنَا عَلَىٰٓ ءَاذَانِهِمْ فِى ٱلْكَهْفِ سِنِينَ عَدَدًا

So We cast [a cover of sleep] over their ears within the cave for a number of years.

Translation: Saheeh International

Tafsir

So We smote their ears that is We made them sleep in the Cave for several years for a fixed number of years.

Excerpt from Tafsir al-Jalalayn, commentary on 18:11, via Quran.com. The reader has the full commentary and 9 more tafsirs.