But beware of false prophets, which come to you in sheep's clothing, but within are ravening wolves.
By their fruits ye shall know them. Do [men] gather a bunch of grapes from thorns, or from thistles figs?
So every good tree produces good fruits, but the worthless tree produces bad fruits.
A good tree cannot produce bad fruits, nor a worthless tree produce good fruits.
Every tree not producing good fruit is cut down and cast into the fire.
By their fruits then surely ye shall know them.
References for Matthew 7:20