Numbers 21:9
7 Then the people came to Moses and said, “We have sinned, for we have spoken against the Lord and against you. Pray to the Lord that he would take away the snakes from us.” So Moses prayed for the people. 8 The Lord said to Moses, “Make a poisonous snake and set it on a pole. When anyone who is bitten looks at it, he will live.” 9 So Moses made a bronze snake and put it on a pole, so that if a snake had bitten someone, when he looked at the bronze snake he lived. 10 The Israelites traveled on and camped in Oboth. 11 Then they traveled on from Oboth and camped at Iye Abarim, in the wilderness that is before Moab on the eastern side.
2 Kings 18:4
2 He was twenty-five years old when he began to reign, and he reigned twenty-nine years in Jerusalem. His mother was Abi, the daughter of Zechariah. 3 He did what the Lord approved, just as his ancestor David had done. 4 He eliminated the high places, smashed the sacred pillars to bits, and cut down the Asherah pole. He also demolished the bronze serpent that Moses had made, for up to that time the Israelites had been offering incense to it; it was called Nehushtan. 5 He trusted in the Lord God of Israel; in this regard there was none like him among the kings of Judah either before or after. 6 He was loyal to the Lord and did not abandon him. He obeyed the commandments that the Lord had given to Moses.
Notes and References
"... Jews of later ages surely did believe that no other gods but their own are real, so how did monotheism arise? What led the people of Israel to such a radical conclusion? There is a hint about the answer to this question in the narrative of biblical history. The historical books of scripture describe a development that would recur every few generations: the appearance of a religious reformer who would attack the nation’s tendency to idolatry and demand the removal of previously acceptable customs. For example, the Torah relates that when “fiery serpents” invaded Israel’s encampment in the desert, Moses himself crafted a similar creature out of bronze or copper and set it up to view: “if a [living] serpent bit a man, he gazed upon the copper serpent and lived” (Numbers 21:9). One might have thought that the copper serpent’s association with Moses gave it legitimacy, but years later the reforming King Hezekiah destroyed it, even though he knew that Moses himself had made it, because “the people of Israel had offered it incense, calling it Nehushtan.” (2 Kings 18:4 ... The name is a play on the Hebrew word nehoshet, meaning “bronze” or “copper.”) Over the centuries, many objects of veneration were thus excluded from the life of the nation, until finally only one God was left ..."
Goldenberg, Robert The Origins of Judaism: From Canaan to the Rise of Islam (p. 34) Cambridge University Press, 2007