And thereupon We veiled their ears in the cave for many a year,

Then We draw (a veil) over their ears, for a number of years, in the Cave, (so that they heard not):

Then We sealed up their hearing in the Cave for a number of years.

So We prevented them from hearing in the Cave for a number of years,

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