Joshua 8:2

8:2 And thou shalt do to Ai and her king as thou didst unto Jericho and her king: only the spoil thereof, and the cattle thereof, shall ye take for a prey unto yourselves: lay thee an ambush for the city behind it.

Joshua 8:4

8:4 And he commanded them, saying, Behold, ye shall lie in wait against the city, [even] behind the city: go not very far from the city, but be ye all ready: