Thematic Bible: What proceeds from the heart

Then calling out to the crowd, he addressed them, "Listen and understand! It is not what goes into the mouth that makes a person unclean. It is what comes out of the mouth that makes a person unclean."

Then he called to the crowd again and told them, "Listen to me, all of you, and understand! Nothing that goes into a person from the outside can make him unclean. It's what comes out of a person that makes a person unclean. If anyone has ears to hear, let him listen!" read more.
When he had left the crowd and gone home, his disciples began asking him about the parable. He asked them, "Are you so ignorant? Don't you know that nothing that goes into a person from the outside can make him unclean? Because it doesn't go into his heart but into his stomach, and then into the sewer, thereby expelling all foods." Then he continued, "It's what comes out of a person that makes a person unclean, because it's from within, from the human heart, that evil thoughts come, as well as sexual immorality, stealing, murder, adultery, greed, wickedness, cheating, shameless lust, envy, slander, arrogance, and foolishness. All these things come from inside and make a person unclean."