And having called the multitudes to him. Here Christ turns [1] to those who are ready to receive instruction, and explains more fully the truth at which he had formerly glanced, that the kingdom of God does not consist in meat and drink, as Paul also teaches us, (Romans 14:17;) for, since outward things are by nature pure, the use of them is free and pure, and uncleanness is not contracted from the good creatures of God. It is therefore a general statement, that pollution does not come from without into a man, but that the fountain is concealed within him. Now when he says that all the evil actions which any man performs come out of the mouth of man, he employs a synecdoche; [2] for he says so by way of allusion to the subject in hand, and conveys this instruction, that we do not draw uncleanness into our mouth along with meat and drink, but that every kind of defilement proceeds from ourselves. Knowest thou that the Pharisees were offended? As the scribes were presumptuous and rebellious, Christ did not take great pains to pacify them, but satisfied himself with repelling their hypocrisy and pride. The offense which they had formerly taken up was doubled, when they perceived that--not through oversight, but seemingly on purpose--Christ despised their washings as trifles. Now when Christ did not hesitate to inflame still more, by keen provocation, wicked and malicious persons, let us learn from his example, that we ought not to be exceedingly solicitous to please every one by what we say and do. His disciples, however--as is usually the case with ignorant and unlearned people--no sooner perceive the result to be unfavorable, than they conclude that Christ's reply had been unseasonable and improper. [3] For the object of their advice was, to persuade Christ to soothe the rage of the Pharisees by softening the harsh expression which he had employed. [4] It almost always happens with weak persons, that they form an unfavorable judgment about a doctrine, as soon as they find that it is regarded with doubt or meets with opposition. And certainly it were to be wished, that it should give no offense, but receive the calm approbation of all; but, as the minds of many are blinded, and even their hearts are kindled into rage, by Satan, and as many souls are held under the benumbing influence of brutal stupidity, it is impossible that all should relish the true doctrine of salvation. Above all, we ought not to be surprised to behold the rage of those who inwardly nourish the venom of malice and obstinacy. Yet we ought to take care that, so far as may be in our power, our manner of teaching shall give no offense; but it would be the height of madness to think of exercising greater moderation than we have been taught to do by our heavenly Master. We see how his discourse was made an occasion of offense by wicked and obstinate men; and we see at the same time, how that kind of offense which arose from malignity was treated by him with contempt.

Footnotes

1 - "Christ laissant la ces orgueilleux, se retourne vers les dociles;" -- "Christ, leaving there these proud men, turns towards the teachable."

2 - "Au reste, quand il dit que les maux qu'un chacun fait procedent de la bouche, c'est autant comme s'il disoit qu'ils procedent de la personne mesme; et c'est une figure et maniere de parler qu'on appelle Synecdoche, quand on prend une partie pour le tout;" -- "besides, when he says that the evils which any man does proceed out of the mouth, it is as much as if he said that they proceed from the person himself; and it is a figure and way of speaking that is called Synecdoche, when a part is taken for the whole."

3 - "Voyans que le propos n'avoit pas este bien prins, il leur semble avis que Christ a respondu peu autrement qu'il ne faloit;" -- "perceiving that the discourse was not well taken, they conclude that Christ had replied somewhat differently from what he ought to have done."

4 - "En redressant ce qu'il avoit dit un peu trop asprement, comme il leur sembloit;" -- "by correcting what he had said a little too harshly, as they imagined."

See also Mark 7:15-17.
And he called the multitude - In opposition to the doctrines of the Pharisees, the Saviour took occasion to show them that the great source of pollution was the heart. They supposed that external things chiefly defiled a man. On this all their doctrines about purification were founded. This opinion of the Jews it was of great importance to correct. The Saviour took occasion, therefore, to direct the people to the true source of defilement - their own hearts. He particularly directed them to it as of importance - "Hear and understand."

Hear and understand - A most important command. Hear - make it a point of conscience to attend to the ministry of the word. Understand - be not satisfied with attending places of public worship merely; see that the teaching be of God, and that you lay it to heart.

(4) And he called the multitude, and said unto them, Hear, and understand:
(4) Christ teaches us that the hypocrisy of false teachers who deceive our souls is not to be endured at all, not even in small matters, and there is no reason why their office or position should blind our eyes: otherwise we are likely to perish with them.

And he called the multitude,.... Having silenced the Scribes and Pharisees, and judging it not worth his while to say any more to men so obstinate and perverse; who were not open to conviction, nor would attend to any argument or reason, though ever so clear and strong, against their darling notions; he leaves them, as both disliking them, and despairing of them, and calls to the common people; who, through their great veneration for these men, upon their coming withdrew, and stood at a distance; nor indeed would they admit them very near unto them, lest they should be polluted by them: Christ, I say, calls to these to come nearer to him, hoping better of them, and knowing that they were more tractable, and teachable; and that there were some among them, that were to be brought off of their former principles and prejudices, to embrace him, and the truths delivered by him:
and said unto them, hear and understand; this he said, partly, by way of reflection upon the learned Scribes and Pharisees, who, with all their learning, could not hear him so as to understand him; and partly to excite the attention of the multitude to what he had to say; as also to show, that barely to hear with the outward hearing of the ear, will be of no service, unless what is heard is understood; and that the way to understand, is to hear.

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, Jeremiah 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.

And he called the multitude, and said unto them--The foregoing dialogue, though in the people's hearing, was between Jesus and the pharisaic cavillers, whose object was to disparage Him with the people. But Jesus, having put them down, turns to the multitude, who at this time were prepared to drink in everything He said, and with admirable plainness, strength, and brevity, lays down the great principle of real pollution, by which a world of bondage and uneasiness of conscience would be dissipated in a moment, and the sense of sin be reserved for deviations from the holy and eternal law of God.
Hear and understand:

He called the multitude. In order to show them that the Pharisaical expounders of the law did not understand its real sense.
Not that which goeth into a man defileth. The Mosaic law forbade Jews to eat what was ceremonially unclean, in order to teach the need of moral purity. The Rabbins 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 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 Matthew 15:18-23.