Num 21:6-9

6Then the Lord sent poisonous serpents among the people, and they bit the people, so that many Israelites died.7The people came to Moses and said, “We have sinned by speaking against the Lord and against you; pray to the Lord to take away the serpents from us.” So Moses prayed for the people.8And the Lord said to Moses, “Make a poisonous serpent, and set it on a pole; and everyone who is bitten shall look at it and live.”9So Moses made a serpent of bronze, and put it upon a pole; and whenever a serpent bit someone, that person would look at the serpent of bronze and live.