Numbers 21:4-9

4And they journeyed from mount Hor by the way of the Red sea, to compass the land of Edom: and the soul of the people was much discouraged because of the way.1 5And the people spake against God, and against Moses, Wherefore have ye brought us up out of Egypt to die in the wilderness? for there is no bread, neither is there any water; and our soul loatheth this light bread. 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.