And he sacrificed and burned incense on the high places, and on the hills, and under every green tree.

and he sacrificeth and maketh perfume in high places, and on the heights, and under every green tree.

And he made offerings, burning them in the high places and on the hills and under every green tree.

And he sacrificed and offered in the high places, and on the hills, and under every leafy tree.

Also, he was immolating victims, and burning incense, in the high places, and on the hills, and under every leafy tree.

He sacrificed - Other kings of Judah bad allowed their people to do so. Ahaz was the first, so far as we know, to countenance the practice by his own example.

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.