I fast twice in the week, I give tithes of all that I possess. This is equivalent to saying that he performed more than the law required; just as the Popish monks talk loftily of their works of supererogation, as if they found no great difficulty in fulfilling the law of God. It must be admitted that each of us, according to the measure of the virtues which God has bestowed upon him, is the more strongly bound to thank the Author of them; and that it is an exercise of holy meditation for each of us to ponder on the benefits which he has received, so as not to bury in ingratitude the kindness of God. But there are two things here that must be observed: we must not swell with confidence, as if we had satisfied God; and, next, we must not look down with disdainful contempt upon our brethren. In both respects the Pharisee erred; for, by falsely claiming righteousness for himself, he left nothing to the mercy of God; and, next, he despised all others in comparison of himself. And, indeed, that thanksgiving would not have been disapproved by Christ, if it had not labored under these two defects; [1] but as the proud hypocrite, by winking at his sins, met the justice of God with a pretense of complete and perfect righteousness, his wicked and detestable hardihood could not but make him fall. For the only hope of the godly, so long as they labor under the weakness of the flesh, is, after acknowledging what is good in them, [2] to betake themselves to the mercy of God alone, and to rest their salvation on prayer for forgiveness. [3] But it may be asked, how did this man, who was blinded by wicked pride, maintain such sanctity of life; for such integrity proceeds only from the Spirit of God, who, we are certain, does not reign in hypocrites? I reply: he trusted only to outward appearance, as if the hidden and inward uncleanness of the heart would not be taken into the account. Though he was full of wicked desires within, yet as he looks only at the appearance, he boldly maintains his innocence. Our Lord does not, indeed, accuse him of vanity, in falsely claiming for himself what he does not possess; but it ought to be believed that no man is pure from extortion, injustice, uncleanness, and other vices, unless he is governed by the Spirit of God. The word Sabbath (sabbaton) denotes in this passage, as in many others, a week But God never enjoined in the Law that his servants should fast every week; so that this fasting and the tithes were voluntary exercises beyond the prescriptions of the Law. [4]

Footnotes

1 - "Si ces deux vices n'y estoyent, qui gastent tout;" -- "if those two faults had not been in it, which spoil the whole."

2 - "Apres avoir recognu le bien qui est en eux par la grace de Dieu;" -- "after having acknowledged the good that is in them by the grace of God."

3 - "Et mettre leur salut en la confession de leurs pechez, et remission d'iceux;" -- "and to place their salvation in the confession of their sins, and forgiveness of them."

4 - "Estoyent des exercises volontaires, et inventez a plaisir;" -- "were voluntary exercises, and invented at pleasure."

I fast twice - This was probably the Jewish custom. The Pharisees are said to have fasted regularly on the second and fifth days of every week in private. This was "in addition" to the public days of fasting required in the law of Moses, and they, therefore, made more a matter of "merit" of it because it was voluntary.
I give tithes - A tithe means the tenth part of a thing. A tenth part of the possessions of the Jews was required for the support of the Levites, Numbers 18:21. In addition to the tithes required strictly by law, the Pharisees had tithed everything which they possessed even the smallest matters - as mint, anise, cummin, etc., Luke 11:42. It was "this," probably, on which he so particularly prided himself. As this could not be proved to be strictly "required" in the law, it had more the "appearance" of great piety, and, therefore, he particularly dwelt on it.
I possess - This may mean either all which I "have," or all which I "gain" or acquire. It is not material which meaning be considered the true one.
The religion of the Pharisee, therefore, consisted in:
1. abstaining from injustice to others; in pretending to live a harmless, innocent, and upright life; and,
2. a regular observance of all the external duties of religion.
His "fault" consisted in relying on this kind of righteousness; in not feeling and acknowledging that he was a sinner; in not seeking a religion that should dwell in the "heart" and regulate the feelings; and in making public and ostentatious professions of his own goodness. Most of all was this abominable in the sight of God, who "looks into the heart," and who sees wickedness there when the external actions may be blameless. We may learn from the case of the Pharisee:
1. That it is not the man who has the most orthodox belief that has, of course, the most piety;
2. That people may be externally moral, and not be righteous in the sight of God;
3. That they may be very exact in the external duties of religion, and even go beyond the strict letter of the law; that they may assume a great appearance of sanctity, and still be strangers to true piety; and,
4. That ostentation in religion, or a "boasting" before God of what we are and of what we have done, is abominable in his sight. This spoils everything, even if the life "should be" tolerably blameless, and if there should be real piety.

I give tithes of all that I possess - Or, of all I acquire, κτωμαι.
Raphelius has well observed, that this verb, in the present tense, signifies to acquire - in the preter, to possess: the Pharisee's meaning seems to be, "As fast as I gain any thing, I give the tenth part of it to the house of God and to the poor." Those who dedicate a certain part of their earnings to the Lord should never let it rest with themselves, lest possession should produce covetousness. This was the Pharisee's righteousness, and the ground on which he builded his hope of final salvation. That the Pharisees had a strong opinion of their own righteousness, the following history will prove: -
"Rabbi Simeon, the son of Jochai, said: The whole world is not worth thirty righteous persons, such as our father Abraham. If there were only thirty righteous persons in the world, I and my son should make two of them; but if there were but twenty, I and my son would be of the number; and if there were but ten, I and my son would be of the number: and if there were but five, I and my son would be of the five; and if there were but two, I and my son would be those two; and if there were but one, myself should be that one." Bereshith Rabba, s. 35, fol. 34. This is a genuine specimen of Pharisaic pride. No wonder that our Lord accused these of pride and vain glory: they were far from humility, and consequently far from righteousness.

I fast twice in the week,.... Not "on the sabbath", as the words may be literally rendered, and as they are in the Vulgate Latin and Ethiopic versions; for the sabbath was not a fasting, but a feasting day with the Jews; for they were obliged to eat three meals, or feasts, on a sabbath day, one in the morning, another at evening, and another at the time of the meat offering: even the poorest man in Israel, who was maintained by alms, was obliged to keep these three feasts (f). It was forbidden a man to fast, until the sixth hour, on a sabbath day; that is, till noon (g): wherefore, it is a great mistake in Justin (h) and Suetonius (i), that the sabbath was kept by the Jews as a fast. But the word is rightly rendered, "in the week"; the whole seven days, or week, were by the Jews commonly called the sabbath; hence, , "the first of the sabbath", and the second of the sabbath, and the third of the sabbath (k); that is, the first, second, and third days of the week. Now the two days in the week on which they fasted were Monday and Thursday, the second and fifth days; on which days the law of Moses, and the book of Esther were read, by the order of Ezra (l); and fasts for the congregation were appointed on those days (m); and so a private person, or a single man, as in this instance, took upon him, or chose to fast on the same (n): the reason of this is, by some, said to be, because Moses went up to Mount Sinai on a Thursday, and came down on a Monday (o). But though these men fasted so often, they took care not to hurt themselves; for they allowed themselves to eat in the night till break of day. It is asked (p),
"how long may a man eat and drink, i.e. on a fast day? until the pillar of the morning ascends (day breaks); these are the words of Rabbi (Judah): R. Eliezer ben Simeon says, until cock crowing.''
So that they had not so much reason to boast of these performances: he adds,
I give tithes of all that I possess; not only of what was tithable by the law of Moses, as the produce of his ground; and by the traditions of the elders, as the herbs in his garden, Matthew 23:23 but of every thing he had, which was not required by either of them; upon which he thought himself a very righteous person, and more than a common man: it is asked (q),
"who is a plebeian? (one of the people of the earth, or the common people) whoever does not eat his common food with purity with hands washed; these are the words of R. Meir; but the wise men say, whoever does not tithe his fruit.''
This man would not be thought to be such an one.
(f) Maimon. Hilch. Sabbat, c. 30. sect. 9. (g) T. Hieros. Nedarim, fol. 40. 4. (h) L. 36. c. 2. (i) Octav. Aug. c. 76. (k) Maimon. Hilch. Mechosre Caphara, c. 2. sect, 8. (l) T. Bab. Bava Kama, fol. 82. 1. Megilla, 31. 1, 2. (m) Maimon. Hilchot Taaniot, c. 1. sect. 5. (n) T. Bab. Taanith, fol. 12. 1. (o) Godwin Moses & Aaron, l. 1. c. 10. Vid. T. Bab. Sabbat, fol. 88. 1. (p) T. Bab. Taanith, fol. 12. 1. (q) T. Bab. Gittin, fol. 61. 1.

I fast twice in the week - So did all the strict Pharisees: every Monday and Thursday. I give tithes of all that I possess - Many of them gave one full tenth of their income in tithes, and another tenth in alms. the sum of this plea is, I do no harm: I use all the means of grace: I do all the good I can.