Numbers 21:6-9

6And Yhwh sent fiery serpents among the people, and they bit the people; and much people of Israel died.

7Therefore the people came to Moses, and said, We have sinned, for we have spoken against Yhwh, and against thee; pray unto Yhwh, that he take away the serpents from us. And Moses prayed for the people. 8And Yhwh said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live. 9And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.