Therefore: The transition word used in Hebrew here is rather strong. It serves to introduce the concluding section of this chapter.
Thus says the LORD: See the comments on verse 20. Since this is a continuation of the message from Yahweh (through Isaiah), some translators prefer to omit this repetitious element. But it seems to be repeated for emphasis, and this emphasis should be retained in translation where possible. Contemporary English Version simply has “I promise” in place of thus says the LORD, so that the direct quotation of the LORD is not interrupted.
The embedded quotation of the LORD within this verse may have to be made indirect in certain languages.
He shall not come into this city: This statement and those that follow are stated in terms of the singular pronoun He. But the Assyrian king represents his whole army and the meaning certainly includes the whole group. In some languages it will be better to change the subject from the beginning and say something like “he and his soldiers will never enter this city.” The rest of this verse refers to the way in which Assyrian armies conquered walled cities. Soldiers protected by shields shot arrows against the defenders of the city walls so that other soldiers could build ramps by which to go over the top of the city walls.
Shoot an arrow there: Once again, it is not only the king who will be unable to shoot an arrow into the city. None of his forces will do so. Some may prefer to say something like “not even a single arrow will land inside the city.”
Come before it with a shield: The Assyrian soldiers with their battle shields will be unable even to approach the walls of Jerusalem. Good News Translation says “No soldiers with shields will come near the city.” For shield see the comments on 1 Kgs 10.17.
Cast up a siege mound against it: Since one of the most important tactics in capturing an enemy city was the siege (see 1 Kgs 15.27), this promise emphasizes the fact that the Assyrians will also be unable to use this tactic. A possible model translation for languages where the procedure mentioned here is unknown is “build a ramp to attack the city walls” (New Century Version).
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Kings, Volume 2. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here .