Albert Barnes Commentary Isaiah 38:6

"And I will deliver thee and this city out of the hand of the king of Assyria; and I will defend this city." — Isaiah 38:6 (ASV)

And I will deliver thee and this city – The meaning of this promise is that he and the city would be finally and entirely delivered from all danger of invasion from the Assyrians.

It might be feared that Sennacherib would collect a large army and return, or that his successor would prosecute the war which he had begun. But the assurance here is given to Hezekiah that he had nothing more to fear from the Assyrians (see the notes at Isaiah 31:4-5; Isaiah 37:35).

In the parallel passage in 2 Kings 20:6, it is added: I will defend this city for mine own sake, and for my servant David’s sake. Also, in the parallel passage in 2 Kings 20:7–8, the statement is inserted that occurs in Isaiah at the end of the chapter (Isaiah 38:21–22).

It is evident that those two verses more appropriately come in here. Lowth suggests that the abridger of the history omitted those verses. When he had transcribed the song of Hezekiah, he saw that they were necessary to complete the narrative and placed them at the end of the chapter with proper marks to have them inserted in the right place. These marks, however, were overlooked by transcribers. It is, however, immaterial where the statement is made, and it is now impossible to tell how the transposition occurred.