Charles Ellicott Commentary 2 Chronicles 21:6

"And he walked in the way of the kings of Israel, as did the house of Ahab; for he had the daughter of Ahab to wife: and he did that which was evil in the sight of Jehovah." — 2 Chronicles 21:6 (ASV)

And he walked in the way. —A repetition of 2 Kings 8:18, word for word.