Deuteronomy 20:19-20

19When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees of it by forcing an axe against them: for thou mayest eat of them, and thou shalt not cut them down (for the tree of the field is man’s life ) to employ them in the siege:12 20Only the trees which thou knowest that they are not trees for food, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it shall be subdued.3