The heart of the king shall perish. — The heart, as representing the mind generally. Judgment and wisdom were to give way to panic and fear.
Related Commentaries of Jeremiah 4:9
Jeremiah 4:9
9 And it shall come to pass at that day, saith the LORD, that the heart of the king shall perish, and the heart of the princes; and the priests shall be astonished, and the prophets shall wonder.