Isaias 58:4

He says then to them again concerning these things, “Why do ye fast to Me as on this day, saith the Lord, that your voice should be heard with a cry? I have not chosen this fast, saith the Lord, that a man should humble his soul. Nor, though ye bend your neck like a ring, and put upon you sackcloth and ashes, will ye call it an acceptable fast.” To us He saith, “Behold, this is the fast that I have chosen, saith the Lord, not that a man should humble his soul, but that he should loose every band of iniquity, untie the fastenings of harsh agreements, restore to liberty them that are bruised, tear in pieces every unjust engagement, feed the hungry with thy bread, clothe the naked when thou seest him, bring the homeless into thy house, not despise the humble if thou behold him, and not [turn away] from the members of thine own family. …

“Learn, therefore, to keep the true fast of God, as Isaiah says, that you may please God. Isaiah has cried thus: ‘Shout vehemently, and do not spare: lift up thy voice as with a trumpet, and show My people their transgressions, and the house of Jacob their sins. They seek Me from day to day, and desire to know My ways, as a nation that did righteousness, and forsook not the judgment of God. They ask of Me now righteous judgment, and desire to draw near to God, saying, Wherefore have we fasted, and Thou seest not? and afflicted our souls, and Thou hast not known? Because in the days of your fasting you find your own pleasure, and oppress all those who are subject to you. Behold, ye fast for strifes and debates, and smite the humble with your fists. …

For, so far as pertains to fasts, they oppose to us the definite days appointed by God: as when, in Leviticus, the Lord enjoins upon Moses the tenth day of the seventh month (as) a day of atonement, saying, “Holy shall be to you the day, and ye shall vex your souls; and every soul which shall not have been vexed in that day shall be exterminated from his people.” At all events, in the Gospel they think that those days were definitely appointed for fasts in which “the Bridegroom was taken away;” and that these are now the only legitimate days for Christian fasts, the legal and prophetical antiquities having been abolished: for wherever it suits their wishes, they recognise what is the meaning of “the Law and the prophets until John.” Accordingly, (they think) that, with regard to the future, fasting was to be indifferently observed, by the New Discipline, of choice, not of command, accord …

4. Finally, beloved brethren, the divine admonition in the Scriptures, as well old as new, has never failed, has never been silent in urging God’s people always and everywhere to works of mercy; and in the strain and exhortation of the Holy Spirit, every one who is instructed into the hope of the heavenly kingdom is com manded to give alms. God commands and prescribes to Isaiah: “Cry,” says He, “with strength, and spare not. Lift up thy voice as a trumpet, and declare to my people their transgressions, and to the house of Jacob their sins.” And when He had commanded their sins to be charged upon them, and with the full force of His indignation had set forth their iniquities, and had said, that not even though they should use supplications, and prayers, and fastings, should they be able to make atonement for their sins; nor, if they were clothed in sackcloth and ashes, be able to soften G …

In Isaiah: “Cry aloud,” saith He, “and spare not; lift up thy voice like a trumpet; tell my people their sins, and the house of Jacob their wickednesses. They seek me from day to day, and desire to know my ways, as a people which did righteousness, and did not forsake the judgment of God. They ask of me now a righteous judgment, and desire to approach to God, saying, What! because we have fasted, and Thou hast not seen: we have humiliated our souls, and Thou hast not known. For in the days of fasting are found your own wills; for either ye torment those who are subjected to you, or ye fast for strifes and judgments, or ye strike your neighbours with fists. For what do you fast unto me, that to-day your voice should be heard in clamour? This fast I have not chosen, save that a man should humble his soul. …

14. For all these things then let us give thanks to God who loveth man; and for His tender care over us, render Him a recompense, that will also be profitable to ourselves; and as regards the commandment which I so frequently discourse of to you, let us use our utmost diligence! For I will not desist from the exhortation until ye are amended: seeing that what we aim at is not that we may address you seldom or frequently, but that we may continue speaking till we have persuaded you. …

News has reached me of the severe persecution carried on against you, and how directly after Easter the men who fast for strife and debate attacked your homes, and gave your labours to the flames, preparing for you indeed a house in the heavens, not made with hands, but for themselves laying up in store the fire which they had used to your hurt. I no sooner heard of this than I groaned over what had happened; pitying not you, my brethren, (God forbid!) but the men who are so sunk in wickedness as to carry their evil deeds to such an extent. …

And so that it is a thing indifferent is very clearly shown from this also; viz., because as it brings justification when observed, so it does not bring condemnation when it is broken in upon; unless perhaps the transgression of a command rather than the partaking of food brings punishment. But in the case of a thing that is good in its own nature, no time should be without it, in such a way as that a man may do without it, for if it ceases, the man who is careless about it is sure to fall into mischief. Nor again is any time given for what is bad in its own nature, because what is hurtful cannot help hurting, if it is indulged in, nor can it ever be made of a praiseworthy character. …