Numbers 21:7-9

7Therefore 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 take away the serpents from us.” So Moses prayed for the people.

8Then the Lord said to Moses, “Make a fiery serpent, and set it on a pole; and it shall be that everyone who is bitten, when he looks at it, shall live.”

9So Moses made a bronze serpent, and put it on a pole; and so it was, if a serpent had bitten anyone, when he looked at the bronze serpent, he lived.