According to the author of 1 Kings, Solomon covered the entire temple with gold to make it beautiful and special for God. This showed how important and precious the temple was, like a special place to talk to God.
1 Kings 6:22: And the whole house he overlaid with gold, until he had finished all the house: also the whole altar that [was] by the oracle he overlaid with gold.
This verse advises against storing treasures on earth, which contradicts the opulence conveyed in 1 Kings 6:22 regarding the use of gold in the temple.
Matthew 6:19: Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal: