on Matthew 6 :16
When ye fast - A fast is termed by the Greeks νηϚις, from νη not, and εσθειν to eat; hence fast means, a total abstinence from food for a certain time. Abstaining from flesh, and living on fish, vegetables, etc., is no fast, or may be rather considered a burlesque on fasting. Many pretend to take the true definition of a fast from Isaiah 58:3, and say that it means a fast from sin. This is a mistake; there is no such term in the Bible as fasting from sin; the very idea is ridiculous and absurd, as if sin were a part of our daily food. In the fast mentioned by the prophet, the people were to divide their bread with the hungry, Isaiah 58:7; but could they eat their bread, and give it too? No man should save by a fast: he should give all the food he might have eaten to the poor. He who saves a day's expense by a fast, commits an abomination before the Lord. See more on Matthew 9:15 (note).
As the hypocrites - of a sad countenance - Σκυθρωποι, either from σκυθρος sour, crabbed, and ωψ the countenance; or from Σκυθης a Scythian, a morose, gloomy, austere phiz, like that of a Scythian or Tartar. A hypocrite has always a difficult part to act: when he wishes to appear as a penitent, not having any godly sorrow at heart, he is obliged to counterfeit it the best way he can, by a gloomy and austere look.
on Matthew 6 :16
Moreover, when ye fast - The word "fast" literally signifies to abstain from food and drink, whether from necessity or as a religious observance. It is, however, commonly applied in the Bible to the latter. It is, then, an expression of grief or sorrow. Such is the constitution of the body, that in a time of grief or sorrow we are not disposed to eat; or, we have no appetite. The grief of the "soul" is so absorbing as to destroy the natural appetites of the "body." People in deep affliction eat little, and often pine away and fall into sickness, because the body refuses, on account of the deep sorrow of the mind, to discharge the functions of health. "Fasting, then, is the natural expression of grief." It is not arbitrary; it is what every person in sorrow naturally does. This is the foundation of its being applied to religion as a sacred rite. It is because the soul, when oppressed and burdened by a sense of sin, is so filled with grief that the body refuses food. It is, therefore, appropriate to scenes of penitence, of godly sorrow, of suffering, and to those facts connected with religion which are suited to produce grief, as the prevalence of iniquity, or some dark impending calamity, or storm, or tempest, pestilence, plague, or famine. It is also useful to humble us, to bring us to reflection, to direct the thoughts away from the allurements of this world to the bliss of a better. It is not acceptable except it be the "real expression," of sorrow; the natural effect of the feeling that we are burdened with crime.
The Jews fasted often. They had four "annual" fasts in commemoration of the capture of Jerusalem Jeremiah 52:7, of the burning of the temple Zechariah 7:3, of the death of Gedaliah Jeremiah 41:4, and of the commencement of the attack on Jerusalem Zechariah 8:19. In addition to these, they had a multitude of occasional fasts. It was customary, also, for the Pharisees to fast twice a week, Luke 18:12.
Of a sad countenance - That is, sour, morose; with assumed expressions of unfelt sorrow.
They disfigure their faces - That is, they do not anoint and wash themselves as usual: they are uncombed, filthy, squalid, and haggard. It is said that they were often in the habit of throwing ashes on their heads and faces; and this, mixing with their tears, served still further to disfigure their faces. So much pains will people take, and so much suffering will they undergo, and so much that is ridiculous will they assume, to impose on God and people. But they deceive neither. God sees through the flimsy veil. Human eyes can pierce a disguise so thin. Hypocrites overact their part. Not having the genuine principles of piety at heart, they know not what is its proper expression, and hence they appear supremely contemptible and abominable. Never should people exhibit outwardly more than they feel; and never should they attempt to exhibit anything for the mere sake of ostentation.
They have their reward - They have all that they desired - the praise of men and "the pleasure of ostentation." See the notes at Matthew 6:2.
on Matthew 6 :16
6:16 When ye fast? - Our Lord does not enjoin either fasting, alms - deeds, or prayer: all these being duties which were before fully established in the Church of God. Disfigure - By the dust and ashes which they put upon their heads, as was usual at the times of solemn humiliation.