Deuteronomy 20:15-19

¹⁵Thus shalt thou do to all the cities that are very far off from thee, not being of the cities of these nations which the Lord thy God gives thee to inherit their land.

¹⁶Of these ye shall not take any thing alive;

¹⁷but ye shall surely curse them, the Chettite, and the Amorite, and the Chananite, and the Pherezite, and the Evite, and the Jebusite, and the Gergesite; as the Lord thy God commanded thee:

¹⁸that they may not teach you to do all their abominations, which they did to their gods, and so ye should sin before the Lord your God.

¹⁹And if thou shouldest besiege a city many days to prevail against it by war to take it, thou shalt not destroy its trees, by applying an iron tool to them, but thou shalt eat of it, and shalt not cut it down: Is the tree that is in the field a man, to enter before thee into the work of the siege?