He removed the high places
Which the best of the kings of Judah never attempted, and which is observed of them to their discredit:
and broke the images, and cut down the groves;
the idols his father set up and served, ( 2 Kings 16:4 ) ( 2 Chronicles 28:24 2 Chronicles 28:26 ) , groves and idols in them, were early instances of idolatry; (See Gill on Judges 3:7), and their use for temples are still continued, not only among some Indian nations F12, but among some Christians in the northern parts of Europe F13;
and brake in pieces the brazen serpent that Moses had made;
which he made in the wilderness, and which was brought by the children of Israel with them into the land of Canaan, and was kept as a memorial of the miracle wrought by looking to it, being laid up in some proper place where it had been preserved to this day:
for unto those days the children of Israel did burn incense to it
not from the time it was brought into Canaan, nor even in later times, in the days of Asa and Jehoshaphat, who would never have suffered it; very probably this piece of idolatry began in the times of Ahaz, who encouraged everything of that kind: for this serpent they had a great veneration, being made by Moses, and a means in his time of healing the Israelites; and they imagined it might be of some service to them, in a way of mediation to God; and worthy of worship, having some degree of divinity, as Kimchi and Ben Gersom; but Laniado F14 excuses them from all show of idolatry, and supposes what they did was for the honour of God only; hence sprung the heresy of the Ophites, according to Theodoret:
and he called it Nehushtan;
perceiving they were ensnared by it, and drawn into idolatry to it, by way of contempt he called it by this name, which signifies "brass"; suggesting that it was only a mere piece of brass, had no divinity in it, and could be of no service to them in divine things; and, that it might no longer be a snare to them, he broke it into pieces; and, as the Jews F15 say, ground it to powder, and scattered it to every wind, that there might be no remains of it.
F12 See Dampier's Voyage, vol. 1. p. 411.
F13 Vid. Fabritii Bibliograph. Antiqu. c. 9. sect. 11.
F14 Cli Yaker, fol. 538. 2.
F15 T. Bab. Avodah Zarah, fol. 44. 1.