Promise 27 from Numbers 21:2-3

Numbers 21:2-3 - "So Israel made a vow to the Lord and said, 'If you will indeed deliver this people into my hand, then I will utterly destroy their cities.' The Lord heard the voice of Israel and delivered up the Canaanites, then they utterly destroyed them and their cities. Thus the name of the place was called Hormah." - The Canaanites began an offensive against the Israelites and they were winning. They had already captured some of them. When the Israelites realised they couldn't do this in their own strength, they regrouped and sought the Lord. Their pleas however wasn't "Lord, save us!" but it was a strategic move in working together with the Lord. The plan was, 'God delivers the Canaanites into their hands', in others words, 'You drive them toward us, and we'll take care of the rest.' This was a vow, or a promise they made to God, but it stems from the realisation that they couldn't do it on their own and needed His help. This wasn't a vow such as "Lord if You help me win the lottery, I'll give to the poor!" but a vow of working together against the enemy. Some people think they have no control over the enemy, so they wait for God to come and wipe him out, but God blesses those who realises the authority they have in taking control of the enemy with God's help.