Numbers 21:4-9

And they journeyed from mount Hor by the way to the Red Sea, to compass the land of Edom: and the soul of the people was much discouraged because of the way. And 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, and there is no water; and our soul loatheth this light bread. And Jehovah sent fiery serpents among the people, and they bit the people; and much people of Israel died. And the people came to Moses, and said, We have sinned, because we have spoken against Jehovah, and against thee; pray unto Jehovah, that he take away the serpents from us. And Moses prayed for the people. And Jehovah said unto Moses, Make thee a fiery serpent, and set it upon a standard: and it shall come to pass, that every one that is bitten, when he seeth it, shall live. And Moses made a serpent of brass, and set it upon the standard: and it came to pass, that if a serpent had bitten any man, when he looked unto the serpent of brass, he lived.