Numbers 21:4-9

They set out from Mount Hor along the Red Sea Road, a detour around the land of Edom. The people became irritable and cross as they traveled. They spoke out against God and Moses: “Why did you drag us out of Egypt to die in this godforsaken country? No decent food; no water—we can’t stomach this stuff any longer.” So GOD sent poisonous snakes among the people; they bit them and many in Israel died. The people came to Moses and said, “We sinned when we spoke out against GOD and you. Pray to GOD; ask him to take these snakes from us.” Moses prayed for the people. GOD said to Moses, “Make a snake and put it on a flagpole: Whoever is bitten and looks at it will live.” So Moses made a snake of fiery copper and put it on top of a flagpole. Anyone bitten by a snake who then looked at the copper snake lived.