Numbers 21:3
And the LORD hearkened to the voice of Israel, and delivered up the Canaanites; and they utterly destroyed them and their cities: and he called the name of the place Hormah. And the LORD hearkened to the voice of Israel, and delivered up the Canaanites; and they utterly destroyed them and their cities: and he called the name of the place Hormah.
King Arad and the Canaanites made war against Israel, gained an initial success, and carried away some of the people as prisoners. This conflict followed Israel's request for passage through Amorite territory, which the king refused while he prepared his forces for battle.
In their distress Israel prayed for the Lord to go with their armies into battle and to deliver the Canaanites into their hands, vowing in return to utterly destroy their enemies and their cities and to remain faithful in following God. The Lord hearkened to their earnest prayer and appeal, went out with their armies, and delivered the Canaanites into their hands. Israel then routed their enemies and utterly destroyed them and their cities and towns, and the name of the place was called Hormah.
The defeat of the Canaanites came because they had rejected the evidence of God's power and had set themselves in opposition to Israel, and though God had long spared these nations their wrongdoing had reached its appointed limit. This victory over King Arad and the Canaanites gave the surrounding nations further evidence of God's power. It stood as a recent answer to prayer that gave Israel hope as another danger approached, and it tested whether they would trust God when difficulties came. Yet instead of producing gratitude and humility and a firmer dependence on God, the victory left the people boastful and self-confident.