Ye shall know them by their fruits. Do men gather grapes of thorns, or
figs of thistles?
Even so every good tree bringeth forth good fruit; but a corrupt tree
bringeth forth evil fruit.
A good tree cannot bring forth evil fruit, neither can a corrupt tree
bring forth good fruit.
Every tree that bringeth not forth good fruit is hewn down, and cast
into fire.
Wherefore by their fruits ye shall know them. Matthew 7:15-20