Charles Ellicott Commentary Isaiah 37:18

"Of a truth, Jehovah, the kings of Assyria have laid waste all the countries, and their land," — Isaiah 37:18 (ASV)

Of a truth, Lord ... —The facts of Rabshakeh’s argument are admitted, but the inference is denied, because the cases were not parallel. The gods of the nations had been cast into the fire (an alternative to their being taken as trophies for the temples of Asshur and Ishtar), but this could never happen to Jehovah, of whom there was no graven image, and He would show that He alone was ruler of the earth and of the heavens.