Joshua 8:2-7

You will destroy them as you destroyed Jericho and its king. But this time you may keep the plunder and the livestock for yourselves. Set an ambush behind the town.” So Joshua and all the fighting men set out to attack Ai. Joshua chose 30,000 of his best warriors and sent them out at night with these orders: “Hide in ambush close behind the town and be ready for action. When our main army attacks, the men of Ai will come out to fight as they did before, and we will run away from them. We will let them chase us until we have drawn them away from the town. For they will say, ‘The Israelites are running away from us as they did before.’ Then, while we are running from them, you will jump up from your ambush and take possession of the town, for the LORD your God will give it to you.