2 Kings 16:4

And he sacrificed and burnt incense in the high places, and on the hills,.... Which none of the kings of Judah before him ever did; for though they connived at this practice in the people, they never encouraged it by their own example; and very probably he offered sacrifices there to idols, see 2 Chronicles 28:25 whereas the people sacrificed to the true God, though at a wrong place:

and under every green tree; and which is never said of the people, and seems to confirm it, that Ahaz sacrificed to other gods, since the Heathens used to place idols under green trees, and worship them, whom the Jews imitated, Jeremiah 2:2.