Then the LORD said to Joshua, “Do not be afraid; do not be discouraged. Take the whole army with you, and go up and attack Ai. For I have delivered into your hands the king of Ai, his people, his city and his land.
References for Joshua 8:1
You shall do to Ai and its king as you did to Jericho and its king, except that you may carry off their plunder and livestock for yourselves. Set an ambush behind the city.”
References for Joshua 8:2
So Joshua and the whole army moved out to attack Ai. He chose thirty thousand of his best fighting men and sent them out at night
with these orders: “Listen carefully. You are to set an ambush behind the city. Don’t go very far from it. All of you be on the alert.
I and all those with me will advance on the city, and when the men come out against us, as they did before, we will flee from them.
They will pursue us until we have lured them away from the city, for they will say, ‘They are running away from us as they did before.’ So when we flee from them,
you are to rise up from ambush and take the city. The LORD your God will give it into your hand.
References for Joshua 8:7