The Sabbath is mentioned at the beginning of the creation [thus]: “And God made in six days the works of His hands, and made an end on the seventh day, and rested on it, and sanctified it.” Attend, my children, to the meaning of this expression, “He finished in six days.” This implies that the Lord will finish all things in six thousand years, for a day is with Him a thousand years. And He Himself testifies, saying, “Behold, to-day will be as a thousand years.” Therefore, my children, in six days, that is, in six thousand years, all things will be finished. “And He rested on the seventh day.” This means: when His Son, coming [again], shall destroy the time of the wicked man, and judge the ungodly, and change the sun, and the moon, and the stars, then shall He truly rest on the seventh day. Moreover, He says, “You shall sanctify it with pure hands and a pure heart.” If, therefore, any one can now sanctify the day which God has sanctified, except he is pure in heart in all things, we are deceived. Behold, therefore: certainly then one properly resting sanctifies it, when we ourselves, having received the promise, wickedness no longer existing, and all things having been made new by the Lord, shall be able to work righteousness. Then we shall be able to sanctify it, having been first sanctified ourselves.
Further, He says to them, “Your new moons and your Sabbath I cannot endure.” You perceive how He speaks: Your present Sabbaths are not acceptable to Me, but that is which I have made, [namely this,] when, giving rest to all things, I shall make a beginning of the eighth day, that is, a beginning of another world. Wherefore, also, we keep the eighth day (Sunday) with joyfulness, the day also on which Jesus rose again from the dead. And when He had manifested Himself, He ascended into the heavens. – ibid
If then those who had walked in ancient practices attained unto newness of hope, no longer observing Sabbaths but fashioning their lives after the Lord’s day, on which our life also arose through Him and through His death which some men deny.
Letter to Diognetus
But again their scruples concerning meats, and their superstition relating to the Sabbath and the vanity of their circumcision and the dissimulation of their fasting and new moons, I do [not] suppose you need to learn from me, are ridiculous and unworthy of any consideration… And again to lie against God, as if He forbad us to do any good thing on the Sabbath day, is not this profane?
The new law requires you to keep perpetual Sabbath, and you, because you are idle for one day, suppose you are pious, not discerning why this has been commanded you: and if you eat unleavened bread, you say the will of God has been fulfilled. The Lord our God does not take pleasure in such observances: if there is any perjured person or a thief among you, let him cease to be so; if any adulterer, let him repent; then he has kept the sweet and true Sabbaths of God. If any one has impure hands, let him wash and be pure.
Do you see that the elements are not idle, and keep no Sabbaths? Remain as you were born. For if there was no need of circumcision before Abraham, or of the observance of Sabbaths, of feasts and sacrifices, before Moses; no more need is there of them now. – ibid
“You hypocrites, does not each one of you on the Sabbath-days loose his ox or his ass, and lead him away to watering? And ought not this woman, being a daughter of Abraham, whom Satan has bound these eighteen years, be loosed from this bond on the Sabbath-days?” It is clear therefore, that He loosed and vivified those who believe in Him as Abraham did, doing nothing contrary to the law when He healed upon the Sabbath-day. For the law did not prohibit men from being healed upon the Sabbaths; [on the contrary,] it even circumcised them upon that day, and gave command that the offices should be performed by the priests for the people; yea, it did not disallow the healing even of dumb animals. Both at Siloam and on frequent subsequent occasions, did He perform cures upon the Sabbath; and for this reason many used to resort to Him on the Sabbath-days. For the law commanded them to abstain from every servile work, that is, from all grasping after wealth which is procured by trading and by other worldly business; but it exhorted them to attend to the exercises of the soul, which consist in reflection, and to addresses of a beneficial kind for their neighbors’ benefit. And therefore the Lord reproved those who unjustly blamed Him for having healed upon the Sabbath-days. For He did not make void, but fulfilled the law, by performing the offices of the high priest, propitiating God for men, and cleansing the lepers, healing the sick, and Himself suffering death, that exiled man might go forth from condemnation, and might return without fear to his own inheritance.
To His disciples He said, who had a priesthood of the Lord, to whom it was lawful when hungry to eat the ears of corn, “For the workman is worthy of his meat.” And the priests in the temple profaned the Sabbath, and were blameless. Wherefore, then, were they blameless? Because when in the temple they were not engaged in secular affairs, but in the service of the Lord, fulfilling the law, but not going beyond it, as that man did, who of his own accord carded dry wood into the camp of God, and was justly stoned to death. – ibid
And in Exodus, God says to Moses: “And you shall observe My Sabbaths; for it shall be a sign between Me and you for your generations.”… But the Sabbaths taught that we should continue day by day in God’s service. “For we have been counted,” says the Apostle Paul, “all the day long as sheep for the slaughter;” that is, consecrated [to God], and ministering continually to our faith, and persevering in it, and abstaining from all avarice, and not acquiring or possessing treasures upon earth. – ibid
It follows, accordingly, that, in so far as the abolition of carnal circumcision and of the old law is demonstrated as having been consummated at its specific times, so also the observance of the Sabbath is demonstrated to have been temporary. … And through this arises the question for us, what Sabbath God willed us to keep? For the Scriptures point to a Sabbath eternal and a Sabbath temporal. For Isaiah the prophet says, “Your Sabbaths my soul hates;” and in another place he says, “My Sabbaths you have profaned.” Whence we discern that the temporal Sabbath is human, and the eternal Sabbath is accounted divine.