John Calvin Commentary Isaiah 37:33

"Therefore thus saith Jehovah concerning the king of Assyria, He shall not come unto this city, nor shoot an arrow there, neither shall he come before it with shield, nor cast up a mound against it." — Isaiah 37:33 (ASV)

Therefore thus says Jehovah. He now returns to the deliverance of which he had formerly spoken. For God promised:

1. that he would drive out Sennacherib;
2. that he would grant food and nourishment for the sustenance of the people, though the country had been wasted and pillaged; and
3. that he would cause that small number to grow into a vast multitude.

Having made these declarations, he returns to the first, because without it all the rest might appear to be useless—that is, if the people were not rescued from the hands of that tyrant.

He shall not enter into the city. God threatens that he will be as a fortress, to hinder him from “entering into the city,” and that he will even meet him, so as to hinder him from coming nearer or fighting against it; for he says that he shall not cast an arrow nor a balister. I think that in this passage סללה (solelah) denotes a balister, or some such machine for throwing darts, rather than a mound; for “mounds” are not thrown or poured.