Deuteronomy 20:19

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:

Ver. 19. Thou shalt not cut them down.] Fruit trees might not be destroyed. Doth God take care for trees? It was to teach us, that if we bring forth fruit fit for God's taste and relish, sanctifying God and Christ in our hearts, we shall not be destroyed. Oaks bring forth apples, such as they are, and acorns, but not fit for meat.