Then the people of Israel set out from Mount Hor, taking the road to the Red Sea to go around the land of Edom. But the people grew impatient along the way,
References for Numbers 21:4
and they began to murmur 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 wretched manna!"
So the LORD sent poisonous snakes among them, and many of them 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 the top of a pole. Those who are bitten will live if they simply look at it!"
So Moses made a snake out of bronze and attached it to the top of a pole. Whenever those who were bitten looked at the bronze snake, they recovered!