Albert Barnes Commentary Isaiah 37:37

"So Sennacherib king of Assyria departed, and went and returned, and dwelt at Nineveh." — Isaiah 37:37 (ASV)

So Sennacherib departed - Probably with some portion of his army and retinue with him, for it is by no means probable that the whole army had been destroyed. In 2 Chronicles 32:21, it is said that the angel cut off all the mighty men of valor, and the leaders and captains in the camp of the king of Assyria. His army was thus entirely disabled, and the loss of so large a part of it, and the consternation produced by their sudden destruction, would of course lead him to abandon the siege.

Went and returned - Went from before Jerusalem and returned to his own land.

And dwelt at Nineveh - How long he dwelt there is not certainly known. Berosus, the Chaldean, says it was ‘a little while’ (see Josephus, Antiquities 10.1.5). Nineveh was on the Tigris, and was the capital of Assyria. For an account of its site, and its present situation, see the American Biblical Repository for January 1837, pages 139-159.