For they also built them high places, and images, and groves, on every high hill, and under every green tree.

Wesley's Notes

14:23 They also - Followed the example of the Israelites, although they were better instructed, and had the temple in their kingdom, and liberty of access to it, and the privilege of worshipping God in his own way, and the counsels, and sermons, and examples of the priests and Levites, and the dreadful example of Israel's horrid apostacy, to caution and terrify them. High places - Which was unlawful, and, now especially when the temple was built, and ready to receive them; unnecessary, and therefore expressed a greater contempt of God and his express command. Groves - Not only after the manner of the Heathens and Israelites, but against a direct and particular prohibition. Under every green tree - The people were universally corrupted: which is prodigious, all things considered, and is a clear evidence of the greatness and depth of the original corruption of man's nature.

King James Translators' Notes

images: or, standing images, or, statues

Matthew Henry's Concise Commentary

14:21-31 Here is no good said of Rehoboam, and much said to the disadvantage of his subjects. The abounding of the worst crimes, of the worst of the heathen, in Jerusalem, the city the Lord had chosen for his temple and his worship, shows that nothing can mend the hearts of fallen men but the sanctifying grace of the Holy Spirit. On this alone may we depend; for this let us daily pray, in behalf of ourselves and all around us. The splendour of their temple, the pomp of their priesthood, and all the advantages with which their religion was attended, could not prevail to keep them close to it; nothing less than the pouring out the Spirit will keep God's Israel in their allegiance to him. Sin exposes, makes poor, and weakens any people. Shishak, king of Egypt, came and took away the treasures. Sin makes the gold become dim, changes the most fine gold, and turns it into brass.