Mark 7:15
There is nothing from without a man, that entering into him can defile him: but the things which come out of him, those are they that defile the man. There is nothing from without a man, that entering into him can defile him: but the things which come out of him, those are they that defile the man.
There is nothing entering a person from outside that can make him unclean, but the things coming out of him are what make him unclean, and this was spoken as part of Christ's answer to the Pharisees and scribes when they publicly accused His disciples of eating with unwashen hands because He and His disciples did not observe the ceremonial washings. The accusation was not that they had broken God's law, but that they had broken rabbinical traditions of ceremonial purification before eating, which professed to guard the law yet were regarded as more sacred than the law itself and were given preference when they collided with the commandments given from Sinai. Those rules of purification were numberless and made life one long struggle against ceremonial defilement in an endless round of washings, turning attention away from the great principles of God's law to trifling distinctions God had never required, while neglect of washing was counted a heinous sin to be punished in this world and the next.
Jesus spoke this word to the multitude and afterward explained it more fully to His disciples. Defilement comes not from without but from within a person, and purity and impurity belong to the soul. A person is defiled by evil thoughts arising from the heart, and by the evil deed, the evil word, and the transgression of the law of God. Neglect of external, man-made ceremonies does not defile a person. The evils that appear in outward conduct reveal the corruption of their inward source.