Charles Ellicott Commentary Joshua 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: set thee an ambush for the city behind it." — Joshua 8:2 (ASV)

Only the spoil thereof, and the cattle thereof, shall ye take — that is, the material spoil, not the persons of the inhabitants. (See Joshua 11:14.) Jericho was treated exceptionally, in that the material spoil was made chêrem, devoted to destruction, as the thing accursed of God.