Not that which goeth into the mouth defileth a man; but that which cometh out of the mouth, this defileth a man.

People's New Testament

15:11 Not that which goeth into the mouth defileth a man. The Mosaic law forbade Jews to eat what was ceremonially unclean, in order to teach the need of moral purity. The Rabbis added stringent precepts to prevent the slightest contact with ceremonial uncleanness, but were careless about moral purity. Christ shows that a pure heart is far more important than clean food, in the ceremonial sense, in the stomach. Pharisees in all ages have paid more attention to the letter than to the spirit, to the symbol than to that which is signified.

That which cometh out of the mouth, this defileth a man. The impure words that indicate an impure heart. What one eats does not render him defiled before God, but what he says. See Mt 15:18-23.

Jamieson-Fausset-Brown Bible Commentary

11. Not that which goeth into the mouth defileth a man; but that which cometh out of the mouth, this defileth a man-This is expressed even more emphatically in Mark (Mr 7:15, 16), and it is there added, "If any man have ears to hear, let him hear." As in Mt 13:9, this so oft-repeated saying seems designed to call attention to the fundamental and universal character of the truth it refers to.

Matthew Henry's Concise Commentary

15:10-20 Christ shows that the defilement they ought to fear, was not from what entered their mouths as food, but from what came out of their mouths, which showed the wickedness of their hearts. Nothing will last in the soul but the regenerating graces of the Holy Spirit; and nothing should be admitted into the church but what is from above; therefore, whoever is offended by a plain, seasonable declaration of the truth, we should not be troubled at it. The disciples ask to be better taught as to this matter. Where a weak head doubts concerning any word of Christ, an upright heart and a willing mind seek for instruction. It is the heart that is desperately wicked, Jer 17:9, for there is no sin in word or deed, which was not first in the heart. They all come out of the man, and are fruits of that wickedness which is in the heart, and is wrought there. When Christ teaches, he will show men the deceitfulness and wickedness of their own hearts; he will teach them to humble themselves, and to seek to be cleansed in the Fountain opened for sin and uncleanness.