Entereth not into his heart - Does not reach or affect the "mind," the "soul," and consequently cannot pollute it. Even if it should affect the "body," yet it cannot the "soul," and consequently cannot need to be cleansed by a religious ordinance. The notions of the Pharisees, therefore, are not founded in reason, but are mere "superstition."
The draught - The sink, the vault. "Purging all meats." The word "purging," here, means to purify, to cleanse. What is thrown out of the body is the innutritious part of the food taken into the stomach, and leaving only that which is proper for the support of life; and it cannot, therefore, defile the soul.
All meals - All food; all that is taken into the body to support life. The meaning is, that the economy or process by which life is supported "purifies" or "renders nutritious" all kinds of food. The unwholesome or innutritious parts are separated, and the wholesome only are taken into the system. This agrees with all that has since been discovered of the process of digestion and of the support of life. The food taken into the stomach is by the gastric juice converted into a thick pulp called chyme. The nutritious part of this is conveyed into small vessels, and changed into a milky substance called "chyle." This is poured by the thoracic duct into the left subclavian vein and mingles with the blood, and conveys nutriment and support to all parts of the system. The useless parts of the food are thrown off.

Into the draught - See on Matthew 15:17 (note).
Purging all meats? - For what is separated from the different aliments taken into the stomach, and thrown out of the body, is the innutritious parts of all the meats that are eaten; and thus they are purged, nothing being left behind but what is proper for the support of the body.

Because it entereth not into his heart, but into the belly, and goeth out into the draught, (h) purging all meats?
(h) For that which goes into the draught purges all meats.

Because it entereth not into his heart,.... Which is the seat and fountain of all moral pollution; and if that is not defiled, no other part can be; and that that is not defiled by eating and drinking, unless in case of intemperance, is clear; because food and drink do not go into it:
but into the belly; it is taken in at the mouth, goes down the throat, and is received into the stomach, and from thence it passes through the bowels:
and goeth into the draught; , "the private house", as the Jews call it, without going into the heart at all:
purging all meats; that which it leaves behind, is pure and nourishing; and whatever is gross and impure, is carried with it into the draught, so that nothing remains in the man that is defiling.

Purging all meats - Probably the seat was usually placed over running water.