They deck it with silver and with gold
Cover it with plates of silver and gold, for the sake of
ornament, that it may look grand, majestic, and venerable; and by
this means draw the eye and attention, and so the devotion of
people to it: they fasten it with nails and hammers, that
it move not.
The sense is, either that the idol was fastened to some post or
pillar, or in some certain place on a pedestal, that it might not
fall, it not being able otherwise to support itself; or the
plates of silver and gold, as Kimchi thinks, were fastened to the
idol with nails and hammers, that so they might not be taken away
from it; for, were it not for the nails, the god would not be
able to keep his silver and golden deckings.