Albert Barnes Commentary 1 Kings 14:23

"For they also built them high places, and pillars, and Asherim, on every high hill, and under every green tree;" — 1 Kings 14:23 (ASV)

The words “they also” are emphatic. Not only did the Israelites make high places for themselves (1 Kings 12:31; 1 Kings 13:32), but the people of Judah did as well. The “high places,” which are said to have been “built,” were probably small shrines or tabernacles hung with bright-colored tapestry (Ezekiel 16:16), like the “sacred tent” of the Carthaginians.

The “images” were actually “pillars” (see the note on Genesis 28:18).

Groves – See the note on 1 Kings 14:15. The “groves,” it should be noted, were “built” on high hills and “under green trees.”

Under every green tree – That is, under all the remarkable, solitary trees throughout the land. These trees served as landmarks for their neighborhoods and as resting places for travelers, who gladly sought shelter in their shade (Deuteronomy 12:2).