Deuteronomy 20:19 in the World English Bible
When you shall besiege a city a long time, in making war against it to take it, you shall not destroy its trees by wielding an ax against them; for you may eat of them. You shall not cut them down, for is the tree of the field man, that it should be besieged by you?
Context
18 That they teach you not to do after all their abominations, which they have done unto their gods; so should ye sin against the LORD your God.
19 When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof 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:
20 Only the trees which thou knowest that they be not trees for meat, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it be subdued.