Genesis 2:2

Let us therefore fear, lest, a promise being left us of entering into his rest, any of you should seem to come short of it. For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it. For we which have believed do enter into rest, as he said, As I have sworn in my wrath, if they shall enter into my rest: although the works were finished from the foundation of the world. For he spake in a certain place of the seventh day on this wise, And God did rest the seventh day from all his works. [Genesis 2:2] And in this place again, If they shall enter into my rest. Seeing therefore it remaineth that some must enter therein, and they to whom it was first preached entered not in because of unbelief: Again, he limiteth a certain day, saying in David, To day, after so long a time; as it is said, To day if ye will hear his voice, harden not your hearts. For if Jesus had given them rest, then would he not afterward have spoken of another day. There remaineth therefore a rest to the people of God. For he that is entered into his rest, he also hath ceased from his own works, as God did from his. Let us labour therefore to enter into that rest, lest any man fall after the same example of unbelief. For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart. Neither is there any creature that is not manifest in his sight: but all things are naked and opened unto the eyes of him with whom we have to do.

Further, He says to them, "Your new moons and your Sabbath I cannot endure." Ye 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 with joyfulness, the day also on which Jesus rose again from the dead. And when He had manifested Himself, He ascended into the heavens.

From what toil did God rest? For the creatures that came to be on the first day came to be by implication, except for the light, which came through his word. And the rest of the works that came to be afterward came to be through his word. What toil is there for us when we speak one word? So what toil could there have been for God to speak one word a day? Moses, who divided the sea by his word and his rod, did not tire. Joshua, son of Nun, who restrained the luminaries by his word, did not tire. So what toil could there have been for God when he created the sea and the luminaries by his word? It was not because he rested on that day that God, who does not weary, blessed and sanctified the seventh day. Nor was it because he was to give it to that people, who did not understand that since they were freed from their servitude, they were to give rest to their servants and maidservants. He gave it to them so that, even if they had to be put under requirement, they would rest. It was given to them in order to depict by a temporal rest, which he gave to a temporal people, the mystery of the true rest, which will be given to the eternal people in the eternal world.

You see, in saying at this point that God rested from his works, Scripture teaches us that he ceased creating and bringing from nonbeing into being on the seventh day, whereas Christ, in saying that “my father is at work up until now and I am at work,” reveals his unceasing care for us: he calls “work” the maintenance of created things, bestowal of permanence on them and governance of them through all time. If this wasn’t so, after all, how would everything have subsisted, without the guiding hand above directing all visible things and the human race as well?

(Chapter 2, Verse 2) And on the sixth day God finished his work that he had done, and he rested on the seventh day from all his work that he had done. Therefore, we will refute the Jews, who boast of the rest of the Sabbath, because even then, at the beginning, the Sabbath was dissolved, since God works on the Sabbath, completing his work in it, and blessing the day itself: because in it he has completed everything.

So God completed His work on the seventh day, which He had made. Because He ended the sum of the days He had made in it, adding the seventh itself, which He wanted to be called and to be the Sabbath, because he endows it with mystical blessing and sanctification above the others, as the following teaches. Hence also the day of judgment and consummation of the world, because it is to come after the seventh Sabbath, is called the eighth in the Scriptures, namely because only seven precede it. For it is said in the title of the psalms: To the end, in hymns, for the eighth, a psalm of David, which the entire text of the following psalm teaches is written about the day of judgment, in which the prophet, fearing the wrath of the coming judge, exclaims: Lord, do not rebuke me in Your anger, nor chasten me in Your wrath (Psalm VI, 1), etc. But also the day of the Lord's Resurrection, although it was to come after so many thousands of days, is also called the eighth in the title of another psalm, because naturally it follows the seventh, so that it exists as the first of the following week, that is, the same one in which God said in the beginning: Let there be light and there was light. The psalm written about the Lord's Resurrection indeed proves it by the one speaking in it, saying: For the misery of the needy and the groaning of the poor, now I will arise, says the Lord (Psalm XI, 6). Moreover, it can rightly be accepted that God completed His work on the seventh day, which He had made, even in that He blessed and sanctified that day itself. For blessing and sanctification are not no work. Neither could Solomon be said to have done no work when he dedicated the temple he had made; rather, it is an eminent work of God, when He glorified with eternal blessing and sanctification those things He had made. Finally, about this work which He does in the eternal day of the Sabbath, He says Himself in the parable of the faithful servants: Amen, I say to you that He will gird Himself, and make them sit down to eat, and passing, will serve them (Luke XII, 37). For he who girds himself, who prepares a meal, who passes by, who serves, surely works. But by all these words, nothing else is intimated than that the Lord blesses and sanctifies His saints forever, that is, He rewards them with the vision of His glory after their good works which He gave.

Under the law the people were ordered to work for six days and to rest on the seventh … because the Lord completed the creation of the world in six days and desisted from his work on the seventh. Mystically speaking, we are counseled by all this that those who in life devote themselves to good works for the Lord’s sake are in the future led by the Lord to sabbath, that is, to eternal rest.

And he rested on the seventh day from all his work which he had done. Not as if God rested like a weary man from excessive labor through human frailty after completing the world's creation; but He is said to have rested from all His work, because He ceased to create any new creature thereafter. For Scripture often uses the term "rest" to indicate the cessation of work or speech, as in the Apocalypse about the holy animals: And they have no rest day and night saying: Holy, Holy, Holy, Lord God Almighty (Apoc. IV, 8). Instead of saying they did not cease to always chant this. For the greatest and only rest for the saints in heaven is to declare the praise of the highest Trinity, which is God, with an unfailing voice. It can indeed be understood more profoundly that the Lord rested from all His works, not having any need for those works in which He might rest, since His rest in Himself is always true without beginning and end, but He made His works solely for the sake of His goodness, so that they might rest in Him: which, conversely, is easier to understand when we remember that human necessity particularly insists on daily labors for the purpose of finding rest in its works, as the Lord tells him: By the sweat of your face you shall eat bread (Gen. III, 19). But God, who before the creation of the world had perfect rest in Himself eternally, even after creating the world, did not rest in the works He made, but from all the works He made, as He had no necessity to rest in His creatures, but rather, offering rest to rational creatures, while perfectly always resting in Himself, and being blessed in that good which He alone is to Himself.

Rest is taken in two senses, in one sense meaning a cessation from work, in the other, the satisfying of desire. Now, in either sense God is said to have rested on the seventh day.
First, because He ceased from creating new creatures on that day, for, as said above (1, ad 3), He made nothing afterwards that had not existed previously, in some degree, in the first works; secondly, because He Himself had no need of the things that He had made, but was happy in the fruition of Himself. Hence, when all things were made He is not said to have rested "in" His works, as though needing them for His own happiness, but to have rested "from" them, as in fact resting in Himself, as He suffices for Himself and fulfils His own desire. And even though from all eternity He rested in Himself, yet the rest in Himself, which He took after He had finished His works, is that rest which belongs to the seventh day. And this, says Augustine, is the meaning of God's resting from His works on that day (Gen. ad lit. iv).
God ended: So that, according to our version of the Scripture, the completion of the works is attributed to the seventh day, though according to another (Septuagint) it is assigned to the sixth. Either version, however, may stand, since the completion of the universe as to the completeness of its parts belongs to the sixth day, but its completion as regards their operation, to the seventh.
It would seem that God did not rest on the seventh day from all His work. For it is said (John 5:17), "My Father worketh until now, and I work." God indeed "worketh until now" by preserving and providing for the creatures He has made, but not by the making of new ones.