In Mark 7:14-22, it says,
And he [Jesus]called the people to him again, and said to them, “Hear me, all of you, and understand: there is nothing outside a man which by going into him can defile him; but the things which come out of a man are what defile him.” And when he had entered the house, and left the people, his disciples asked him about the parable. And he said to them, “Then are you also without understanding? Do you not see that whatever goes into a man from outside cannot defile him, since it enters, not his heart but his stomach, and so passes on?” (Thus he declared all foods clean.) And he said, “What comes out of a man is what defiles a man. For from within, out of the heart of man, come evil thoughts, fornication, theft, murder, adultery, coveting, wickedness, deceit, licentiousness, envy, slander, pride, foolishness. All these evil things come from within, and they defile a man.”