And learn therefore to fast the true fast of God, as Isaiah says, in order that ye may please God.
Now Isaiah has cried thus: Cry out with strength, and spare not. Lift up thy voice as with a trumpet and announce to my race their sins and to the house of Jacob their transgressions. Me will they seek day after day, and they long to know my ways, as a people that has done righteousness and not forsaken the judgment of God.
They ask me now for righteous judgement, and long to draw near to God, saying: Why is it that we fasted and Thou didst not see, we humbled our souls, and Thou didst not know? For in the days of your fasts ye find your own desires, and ye sting all those who are under your control. Behold, ye fast for disputes and strifes, and ye strike the lowly with your fists. Why do ye fast to Me until this day, for your voice to be heard in clamour?
This is not the fast that I chose even a day for a man to humble his soul. Nor if thou shouldest bend thy neck as a ring, and spread under thee sackcloth and ashes, not even so shall ye call it a fast and a day acceptable to the Lord. Not such a fast as this did I choose, saith the Lord, but loose every unjust bond, unloose the knots of hard contracts, send away the crushed at liberty, and tear asunder every unjust agreement.
Break thy bread in pieces for the hungry, and gather the poor who have no shelter into thy house. If thou seest one naked, clothe him; and from the kinsmen of thy seed thou shalt not look away in contempt. Then shall thy light break forth in early dawn, and thy clothing spring up quickly, and thy righteousness shall go before thee, and the glory of God shall wrap thee round. Then shalt thou cry out, and the Lord shall hear thee; whilst thou art still speaking He will say, Behold, I am here.
But if thou take away from thee bonds, and stretching out of the hand, and words of murmuring, and give to the hungry thy bread with a willing heart, and fillest the soul brought low, then shall thy light arise in the darkness, and thy darkness be as midday, and thy God shall be with thee continually, and thou shalt be filled as thy soul longeth, and thy bones shall be made fat and shall be as a well-watered garden and a spring of water, or a land for which water never fails.Isaiah 58:1-11
Circumcise therefore the uncircumcision of your heart, as the words of God require throughout all these words.