John Gill Commentary Isaiah 2:21

"to go into the caverns of the rocks, and into the clefts of the ragged rocks, from before the terror of Jehovah, and from the glory of his majesty, when he ariseth to shake mightily the earth." — Isaiah 2:21 (ASV)

To go into the clifts of the rocks, and into the tops of
the ragged rocks
That is, the idolaters shall either go there themselves; or they shall cause their idols to go there, thither they shall cast them; though the former sense seems the best, because of what follows, for fear of the Lord (See Gill on Isaiah 2:10) (See Gill on Isaiah 2:19).