For he rebuilt the high places that his father Hezekiah had destroyed, and he raised up altars for Baal. He made an Asherah pole, as King Ahab of Israel had done, and he worshiped and served all the host of heaven.
How delightful were our meditations on the last reign! How many pleasing views had we of Sion in its glory (that is, in its purity and in its triumphs), of the king in his beauty! (for Isa 33:17 refers to Hezekiah), and (as it follows there, Kg2 21:20) Jerusalem was a quiet habitation because a city of righteousness, Isa 1:26.
Commenting on 2 Kings 21:1-9
For he built up again the high places which Hezekiah his father had destroyed,.... The temples and altars upon them, see Kg2 18:4, and he reared up altars for Baal; in the high places he rebuilt: and made a grove, as did Ahab king of Israel: which was either an idol itself, or a shade of trees where idols were placed; or rather Asherah, rendered...
Made a grove - He made Asherah, the Babylonian Melitta or Roman Venus. See Kg2 17:10, and the observations at the end of that chapter; and see here on Kg2 21:7 (note). Worshipped all the host of heaven - All the stars and planets, but particularly the sun and the moon.