He also. — The pronoun is emphatic: he too, like his father. Kings: “And he walked.”
Walked in the ways of the house of Ahab. — 2 Chronicles 21:6; 2 Chronicles 21:13; Micah 6:16.
For his mother was his counsellor to do wickedly. — Not in Kings; an explanatory remark added by the chronicler. (Comp. 2 Chronicles 20:35; 2 Chronicles 21:6.) Her influence would be used in support of the Baal worship, which was the symbol of alliance with the northern kingdom.