Numbers 28:9

For because they could not have borne it, if when He was giving the law for the Sabbath, He had said, "Do your good works on the Sabbath, but do not the works which are evil," therefore He restrained them from all alike for, "Ye must do nothing at all," saith He: and not even so were they kept in order. But He Himself, in the very act of giving the law of the Sabbath, did even therein darkly signify that He will have them refrain from the evil works only, by the saying, "Ye must do no work, except what shall be done for your life." And in the temple too all went on, and with more diligence and double toil. Thus even by the very shadow He was secretly opening unto them the truth.

The second festival, then, after the festival of the unceasing sacrifice, is set the sacrifice of the sabbath, and every holy and just man ought to keep also the festival of the sabbath. But what is the festival of the sabbath except that of which the Apostle says: "There remaineth therefore a sabbath-keeping," that is, an observance of the sabbath, "for the people of God"? Leaving aside, therefore, the Jewish observances of the sabbath, let us see of what sort the Christian's observance of the sabbath ought to be. On the sabbath day one ought to do no work out of all the works of the world. If, therefore, you cease from all secular works and do nothing worldly, but have leisure for spiritual works, come together to the church, lend an ear to the divine readings and expositions, think upon heavenly things, take thought for the hope to come, keep the judgment that is to come before your eyes, look not to present and visible things but to invisible and future things — this is the Christian's observance of the sabbath. But these things the Jews too ought to observe. Finally, even among them, if a smith, if a builder, and if any workman of this kind there be, he is idle on the sabbath day; but the reader of the divine law or the teacher does not cease from his work, and yet does not defile the sabbath; for so the Lord too says to them: "Have you not read that the priests too in the temple profane the sabbath and are without blame?" He therefore who has ceased from the works of the world and has leisure for spiritual acts, this is he who keeps the sacrifice of the sabbath and the feast day of the sabbaths. Nor does he carry burdens on the way; for every sin is a burden, as the prophet also says: "Like a heavy burden they have weighed upon me." Nor does he kindle a fire — that fire, namely, of which it is said: "Walk in the light of your fire and in the flame which you have kindled." On the sabbath each one sits in his own place and does not go forth from it. What, then, is the place of the spiritual soul? Justice is its place, truth, wisdom, sanctification, and all that Christ is, is the place of the soul. From which place it ought not to go forth, that it may keep the true sabbaths and fulfill the feast day in the sacrifices of the Sabbaths, as the Lord also said: "He who abides in me, and I in him." But as to what we called the true sabbaths, if we seek out…