Luke 6:43-45 (NIV)
43 “No good tree bears bad fruit, nor does a bad tree bear good fruit. 44 Each tree is recognized by its own fruit. People do not pick figs from thornbushes, or grapes from briers. 45 A good man brings good things out of the good stored up in his heart, and an evil man brings evil things out of the evil stored up in his heart. For the mouth speaks what the heart is full of.