John Calvin on Isaiah 37:33

33. Therefore thus saith Jehovah. He now returns to the deliverance of which he had formerly spoken; for God proraised, first, that he would drive out Sennacherib; secondly, that he would grant food and nourishment for the sustenance of the people, though the country had been wasted and pillaged; and, thirdly, that he would cause flint 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.