Albert Barnes Commentary 2 Kings 18:3

"And he did that which was right in the eyes of Jehovah, according to all that David his father had done." — 2 Kings 18:3 (ASV)

He did that which was right ... - This is said without qualification of only three kings of Judah: Asa (1 Kings 15:11), Hezekiah, and Josiah (2 Kings 22:2). See some details of Hezekiah’s acts at the beginning of his reign in 2 Chronicles 29 and following. It is thought that his reformation was preceded, and perhaps caused, by the prophecy of Micah recorded in Jeremiah 26:18 and Micah 3:12.