Joshua 8:2-4

2You shall do [the same] to Ai and its king as you did to Jericho and its king; [except that] you shall take only its spoil and its cattle as plunder for yourselves. Set up an ambush for the city behind it [on the west side].”

3So Joshua set out with all the people of war to go up against Ai; then Joshua chose thirty thousand valiant men, and sent them out at night.

4He commanded them, saying, “Listen closely, you are going to lie in wait and ambush the city from behind it. Do not go very far away from the city, but all of you be ready.