From An Exact Exposition of the Orthodox Faith, Chapter 23

The seventh day is called the Sabbath and signifies rest. For in it God rested from all His works [Gen 2:2], as the divine Scripture says: and so the number of the days goes up to seven and then circles back again and begins at the first. This is the precious number with the Jews. God having ordained that it should be held in honor, and that in no chance fashion but with the imposition of most heavy penalties for the transgression. And it was not in a simple fashion that He ordained this, but for certain reasons understood mystically by the spiritual and clear-sighted.

So far, indeed, as I in my ignorance know, to begin with inferior and more dense things, God, knowing the denseness of the Israelites and their carnal love and propensity towards matter in everything, made this law: first, in order that the servant and the cattle should rest [Dt 5:14] as it is written, for the righteous man regards the life of his beast [Prov 12:10]: next, in order that when they take their ease from the distraction of material things, they may gather together unto God, spending the whole of the seventh day in psalms and hymns and spiritual songs and the study of the divine Scriptures and resting in God. For when the law did not exist and there was no divinely-inspired Scripture, the Sabbath was not consecrated to God. But when the divinely-inspired Scripture was given by Moses, the Sabbath was consecrated to God in order that on it they, who do not dedicate their whole life to God, and who do not make their desire subservient to the as though to a Father, but are like foolish servants, may on that day talk much concerning the exercise of it, and may abstract a small, truly a most insignificant, portion of their life for the service of God, and this from fear of the chastisements and punishments which threaten transgressors. For the law is not made for a righteous man but for the unrighteous [1 Tim 1:9]. Moses, of a truth, was the first to abide fasting with God for forty days and again for another forty, and thus doubtless to afflict himself with hunger on the Sabbaths although the law forbade self-affliction on the Sabbath. But if they should object that this took place before the law, what will they say about Elias the Thesbite who accomplished a journey of forty days on one meal [1 Kgs 19:8]? For he, by thus afflicting himself on the Sabbaths not only with hunger but with the forty days' journeying, broke the Sabbath: and yet God, Who gave the law, was not wroth with him but showed Himself to him on Horeb as a reward for his virtue. And what will they say about Daniel? Did he not spend three weeks without food [Dan 10:2]? And again, did not all Israel circumcise the child on the Sabbath, if it happened to be the eighth day after birth Gen 17:12]? And do they not hold the great fast which the law enjoins if it falls on the Sabbath [Lev 16:31]? And further, do not the priests and the Levites profane the Sabbath in the works of the tabernacle [Mt 12:5] and yet are held blameless? Yea, if an ox should fall into a pit on the Sabbath, he who draws it forth is blameless, while he who neglects to do so is condemned. And did not all the Israelites compass the walls of Jericho bearing the Ark of God for seven days, in which assuredly the Sabbath was included [Jos 3].

As I said, therefore, for the purpose of securing leisure to worship God in order that they might, both servant and beast of burden, devote a very small share to Him and be at rest, the observance of the Sabbath was devised for the carnal that were still childish and in the bonds of the elements of the world [Gal 4:3], and unable to conceive of anything beyond the body and the letter. But when the fulness of the time was come, God sent forth His Only-begotten Son, of a woman, made under the law, to redeem them that were under the law that we might receive the adoption of sons [Gal 4:4]. For to as many of us as received Him, He gave power to become sons of God, even to them that believe on Him [Jn 1:12]. So that we are no longer servants but sons [Gal 4:7]: no longer under the law but under grace: no longer do we serve God in part from fear, but we are bound to dedicate to Him the whole span of our life, and cause that servant, I mean wrath and desire, to cease from sin and bid it devote itself to the service of God, always directing our whole desire towards God and arming our wrath against the enemies of God: and likewise we hinder that beast of burden, that is the body, from the servitude of sin, and urge it forwards to assist to the uttermost the divine precepts.

These are the things which the spiritual law of Christ enjoins on us and those who observe that become superior to the law of Moses. For when that which is perfect is come, then that which is in part shall be done away [1 Cor 13:10]: and when the covering of the law, that is, the veil, is rent asunder through the crucifixion of the Savior, and the Spirit shines forth with tongues of fire, the letter shall be done away with, bodily things shall come to an end, the law of servitude shall be fulfilled, and the law of liberty be bestowed on us. Yea(7) we shall celebrate the perfect rest of bureau nature, I mean the day after the resurrection, on which the Lord Jesus, the Author of Life and our Savior, shall lead us into the heritage promised to those who serve God in the spirit, a heritage into which He entered Himself as our forerunner after He rose from the dead, and whereon, the gates of Heaven being opened to Him, He took His seat in bodily form at the right hand of the Father, where those who keep the spiritual law shall also come.

What belongs to us, therefore, who walk by the spirit and not by the letter, is the complete abandonment of carnal things, the spiritual service and communion with God. For circumcision is the abandonment of carnal pleasure and of whatever is superfluous and unnecessary. For the foreskin is nothing else than the skin which it superfluous to the organ of lust. And, indeed, every pleasure which does not arise from God nor is in God is superfluous to pleasure: and of that the foreskin is the type. The Sabbath, moreover, is the cessation from sin; so that both things happen to be one, and so both together, when observed by those who are spiritual, do not bring about any breach of the law at all.

Further, observe that the number seven denotes all the present time, as the most wise Solomon says, to give a portion to seven and also to eight [Ecc 11:2]. And David, the divine singer when he composed the eighth psalm, sang of the future restoration after the resurrection from the dead. Since the Law, therefore, enjoined that the seventh day should be spent in rest from carnal things and devoted to spiritual things, it was a mystic indication to the true Israelite who had a mind to see God, that he should through all time offer himself to God and rise higher than carnal things.