The LORD sent fiery serpents among the people and they bit the people, so that many people of Israel died. (Numbers 21:6)
The problem with complaining is that God is listening. He hears our words and weighs our hearts. As the Israelites complained about the daily provision of manna, God heard their words and sent a punishment of poisonous snakes. Why did God use snakes to punish Israel?
Rashi explains that God chose snakes for two reasons. The serpent in the Garden of Eden was punished for speaking words of slander against God. God sent the serpent, who was punished for speaking slander, to punish those who were guilty of speaking slander. The second reason was that the serpent had been cursed to eat dust all the days of its life. God sent the serpent, who was punished by being given a diet of dust, to punish those who complained about their food.
When we allow ourselves to slip into self-pity and we give expression to a critical spirit, we are already victims of the evil one. He is a professional slanderer, the accuser of the brethren and the origin of rebellion against God. He was the very first to express discontentment with the lot in life God had assigned to him. When we show ingratitude toward God and complain about His ways, we are speaking the serpent's native tongue. His venom is already poisoning our hearts.
The solution to the problem is repentance. The Israelites went to Moses and said, "We have sinned, because we have spoken against the LORD and you; intercede with the LORD, that He may remove the serpents from us" (Numbers 21:7). Their words encapsulate the gospel message. Yeshua is our Moses. The serpent is the devil. We are the sinners. If we want to be healed and delivered from the serpent, we need to repent, confess our sins and seek forgiveness through Yeshua.
As soon as the Israelites asked Moses for forgiveness, he interceded on their behalf. Rashi points to this as an example for how we should also be quick to forgive others. He says, “From this we learn that a person who is asked for forgiveness should not be so cruel as to withhold forgiveness.” Disciples worthy of Yeshua will be quick to extend forgiveness even to those who have spoken derisively against them or humiliated them.
Moses interceded, and the LORD instructed him to make a bronze serpent. He was to set it atop a pole. When those who were suffering the effects of the venom looked at the serpent, they were cured. “If a serpent bit any man, when he looked to the bronze serpent, he lived” (Numbers 21:9).
How did the serpent on the pole heal the people? The sages explain that it was faith in God and obedience to His command that resulted in miraculous healing, not any magical property of the bronze serpent:
Did the bronze serpent kill or give life? [Of course not.] Rather, when the people of Israel lifted up their eyes [toward heaven] and submitted to their Father in heaven, they were healed. If not, however, they would pine away. (m.Rosh HaShanah 3:8)