Isaiah 10:10

As my hand hath found the kingdoms of the idols, and whose graven images did excel them of Jerusalem and of Samaria;

The verse voices the boast of Assyria as its armies, fresh from conquering the greatest nations of earth and triumphant over Samaria in Israel, turned against Judah. In that boast Assyria claimed that its own power had seized the kingdoms of the idols. It declared that the graven images of those kingdoms excelled those of Jerusalem and of Samaria, and threatened to treat Jerusalem as it had treated Samaria. The boast thus treated the God of Jerusalem as though He were merely an idol like those of the conquered nations, and credited Assyria's victories to its own strength.

Despite that threat from victorious forces, Judah had nothing to fear because its trust was in Jehovah. Confidence that the prophecy against the Assyrians would be fulfilled enabled Hezekiah to stay himself upon God, while the people rested upon his words. For the exercise of faith quickly inspires faith.