Rabbi said: They slandered God again and said, We were dwelling in the land of Egypt in ease and contentment, but the Holy One, blessed be He, and Moses have brought us forth from Egypt to die in the wilderness, as it is said, "And the people spake against God, and against Moses, Wherefore have ye brought us up out of Egypt to die in the wilderness?" (Num. 21:5). What did the Holy One, blessed be He, do unto them?
He sent against them fiery serpents which bit and killed them, as it is said, "And the Lord sent among the people fiery serpents, and they bit the people; and much people of Israel died" (Num. 21:6). Moses beheld the misfortune of Israel, and he arose and prayed on their behalf. The Holy One, blessed be He, said to him: Moses! Make thee a serpent of copper like that serpent || which spoke slander betwixt Adam and his helpmate, and place it on a high place.
Let every man who has been bitten direct his heart to his Father who is in heaven, and let him gaze at that serpent, and he will be healed. Moses made a serpent of copper and set it up in a high place, and every man who had been bitten turned his heart to his Father who is in heaven, and gazed at that serpent, forthwith he became restored to health, as it is said, "And it came to pass, that if a serpent had bitten any man, when he looked at the serpent of copper, he lived" (Num. 21:9); and it also says, "If the serpent bite without enchantment, then is there no advantage in the master of the tongue" (Eccles. 10:11).