“I will.” The text abruptly changes here from third-person speech to first-person speech, with God speaking directly about what He will do.
“punish.” The word is also translated “visit,” but here “punish” is the clearer translation. [For more on “visit,” see commentary on Exodus 20:5].
“arrogant heart.” The Hebrew is more literally, “the greatness of the heart,” idiomatically referring to the arrogance or pride in the heart of the king. The “fruit” of the arrogant heart of the king of Assyria is the words and deeds of the king of Assyria. An evil heart produces evil fruit (see commentary on Matt. 15:18).
“boastfulness of his haughty looks.” The Hebrew is more literally, “the glory of the height of his eyes.” The Hebrew seems unclear, but it is because the text is comparing King of Assyria to a large, glorious fruit tree: he has fruit, glory, and height.
[For more on hypocatastasis, the figure of comparison being used in this verse to compare the king of Assyria to a large fruit tree, see commentary on Rev. 20:2].