Numbers 21:5-9

and they began to speak against God and Moses. “Why have you brought us out of Egypt to die here in the wilderness?” they complained. “There is nothing to eat here and nothing to drink. And we hate this horrible manna!” So the LORD sent poisonous snakes among the people, and many were bitten and died. Then the people came to Moses and cried out, “We have sinned by speaking against the LORD and against you. Pray that the LORD will take away the snakes.” So Moses prayed for the people. Then the LORD told him, “Make a replica of a poisonous snake and attach it to a pole. All who are bitten will live if they simply look at it!” So Moses made a snake out of bronze and attached it to a pole. Then anyone who was bitten by a snake could look at the bronze snake and be healed!