Matthew 7:14-18

Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.

Beware of false prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves.

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.