Luke 6:43-45

For there is no good tree that bears bad fruit, nor, on the other hand, a bad tree that bears good fruit. For each tree is known by its own fruit. For people do not gather figs from thorns, nor do they pick grapes from a briar bush. The good person out of the good treasure of his heart brings forth what is good; and the evil person out of the evil treasure brings forth what is evil; for his mouth speaks from that which fills his heart.