John Gill 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)

And you shall do to Ai and her king as you did to Jericho
and her king
Burn the one and slay the other:

only the spoil thereof, and the cattle thereof, shall you take for a
prey unto yourselves ;
which they were not allowed to do at Jericho:

lay thee an ambush for the city behind it ;
at the west side of it: some have called in question the lawfulness of the ambush, but, as this was appointed by the Lord, there is no room for it.