فَضَرَبْنَا عَلَىٰٓ ءَاذَانِهِمْ فِى ٱلْكَهْفِ سِنِينَ عَدَدًا
Important Words:
ضربنا علی اذانھم (We sealed up their ears). The word ضرب has a vast variety of meanings. They say ضرب علی یدہ i.e. he prevented him from doing a thing that he had begun. ضرب علی اذنه means, he prevented him from hearing. So the Quranic expression ضربنا علی اذانھم means, We prevented them from hearing. It also means, We made them sleep by preventing any sound from penetrating into their ears in consequence of which they would have awoke (Lane & Aqrab). See also 2:274 & 4:35.
Commentary:
Literally the verse means, We prevented any sound from penetrating into their ears, i.e. for a number of years they remained wholly cut off from the affairs of the outside world and did not know what was happening there.
The Arabic expression Daraba‘ala Udhnihi means, he prevented him from hearing. The Quranic expression means, 'We prevented them from hearing.' It also means, 'We made them sleep by preventing any sound from penetrating into their ears in consequence of which they would have awakened' (Lane). Literally, the verse means, 'We prevented any sound from penetrating into their ears,' i.e. for a number of years they remained wholly isolated from the affairs of the outside world and did not know what was happening there.