Charles Ellicott Commentary 2 Kings 19:20

"Then Isaiah the son of Amoz sent to Hezekiah, saying, Thus saith Jehovah, the God of Israel, Whereas thou hast prayed to me against Sennacherib king of Assyria, I have heard [thee]." — 2 Kings 19:20 (ASV)

Then Isaiah ... —The prophet, as Hezekiah’s trusted adviser, may have counselled the king to “go up into the house of the Lord,” or, at least, would be cognisant of his intention in the matter.

Against. —Hebrew text, in regard to.... touching.

I have heard. —The verb has fallen out in Isaiah 37:21.