Unlike when they conquered Jericho,god permitted the Israelites to keep all the spoils of war at Ai,if achan had waited a couple more days,he would have been able to receive from god all the things he wanted.but because he was a human who could not see ahead,he pursed the benefits he could see and sinned.believe that God will provide us with what we need at the right time,so get rid of all greed.