Deuteronomy 20:19-20

19“When you besiege a city for a long time, to make war against it in order to capture it, you shall not destroy its trees by swinging an axe against them; for you may eat from them, so you shall not cut them down. For 1is the tree of the field a human, that it should 2be besieged by you?

20Only the trees that you know 3are not fruit trees you shall destroy and cut down, so that you may construct siegeworks against the city that is making war against you until it falls.