The first being who celebrated the seventh day was אלהים - 'ĕlôhıym (God).
It is said that God did all things on earth, and after creating all things he שׁבת - shâbath {celebrated, rested}.
According to Strongs Hebrew and Greek Dictionaries. The שׁבת - shâbath comes from radical rest, but concerning celebration, not sleeping or being tired. It focuses on stopping work and taking pleasure in something.
For example, a man is working on something, and suddenly his dear son hugs him, and he plays with his son. The action of playing with the child after work is the idea of the term שׁבת - shâbath.
So we have the text:
Gen 2: 2 Now when God had completed the work he had done on the seventh day, he rested on that day from all the work he had done.
Gen 2: 2 ויכל H3615 אלהים H430 ביום H3117 השׁביעי H7637 מלאכתו H4399 אשׁר H834 עשׂה H6213 וישׁבת H7673 ביום H3117 השׁביעי3476 מכ׃ל
In the LXX version we have απο παντων - cease the work. Under no circumstances is the term שׁבת - shâbath- connected with the obligation to be tired. It comes with the connection to obtain joy, happiness or contentment.
If there were only the verse in Genesis 2: 2, we would have that the seventh day, or (ביום H3117 השׁביעי H7637) would be a day to feel joy. But the verse continues:
Gen 2: 3 God blessed the seventh day, and sanctified him; because in him he rested from all his work that he had created and done.
Gen 2: 3 ויברך אלהים את־יום השׁביעי ויקדשׁ אתו כי בו שׁבת מכל־מלאכתו אשׁר־ברא אלהים לעשׂות׃
The verse in Genesis 2: 3 quotes the importance of אבה - shâbath- {celebration, rest} from אלהים - 'ĕlôhıym {God}. The fundamental importance of the Sabbath is that אלהים - 'ĕlôhıym {God} has שׁבת - shâbath- {celebration, rest} on this day.
And so, He blessed אלהים - 'ĕlôhıym {God} the seventh day, and sanctified it.
Was the Sabbath a Jewish invention? It depends on what we believe in the Bible. If the Old Testament is an invention of the Jews, then everything that exists there is a mere invention, and therefore the invention on the part of Moses begins. But if on the contrary we have that the Old Testament is an inspiration of a Divine being, then the Sabbath is not a Jewish invention. For just after the sixth day God שׁבת - shâbath- {celebration, rest}, sanctified and blessed the seventh day, defining it as the seventh day. And saying that the seventh day is the Sabbath, because God "rested on him from all his work that he had created and done". Therefore, it is not a Jewish invention, as it is shortly after the existence of the first human being, and Abraham appears almost two thousand years after God's first שׁבת - shâbath-. God was not Israelite, nor was God a Hebrew to bless and keep the Sabbath. Practiced by God before any nation existed. It is therefore the oldest norm in the Bible.
The term sanctify on the Sabbath - qadash - kaw-dash ', make holy, sacred, dedicate, separate, purify and prepare. Thus, the Sabbath is sacred, using the term qadash - kaw-dash '. If God sanctified the Sabbath, the Sabbath is holy. When did God keep the Sabbath holy? In creation. Since when is the Sabbath holy? Now, do I need to draw? If God sanctifies something, something is holy.
The greatest exponent to be an example of the Sabbath is God Himself. In the absence of nations, or covenants, or human sin, God already sanctified and blessed, the seventh day because it is God's שׁבת - shâbath-.
The Rest שׁבת - shabath which is the term rest of the text. Shabath doesn't define sleep, it defines altering a job to develop a celebration. (That is, give up from exertion; used in many implied relations (causatively, figuratively or specifically): - (cause to, let, make to) cease, celebrate, cause (make) to fail, keep (sabbath), suffer to be lacking, leave, put away (down), (make to) rest, rid, still, take away.). The term means not doing secular works and developing sacred actions. Or rejoicing celebrations. That is, God celebrated the wonderful work of creation, generating the sanctification of the day, and dedicating the divine remembrance of the work.
God follows the law, because he cannot sin so all of God's actions are law, and so all he does is the law so as not to sin. For if the law is the nature of God, everything you do is the norm for everyone. Joh_5: 19 Jesus therefore said to them, Verily, verily, I say to you, the Son of himself can do nothing but what the Father sees him do; because whatever he does, the Son does it equally.
1Co 11: 1 Be my imitators, just as I am of Christ.
Gen 2: 3 God blessed the seventh day, and sanctified him; because in him he rested from all his work that he had created and done.
Linked to the Sabbath, divine rest is linked.
Heb 4: 4 for in a certain place he said thus from the seventh day: And God rested, on the seventh day, from all his works;
Heb 4: 5 and again, in this place: They will not enter my rest.
Heb 4: 6 Therefore, since it remains for some to enter it, and that those to whom the good news was previously preached did not enter because of disobedience,
Thus, the Sabbath is a connection between not being disobedient, since only those who do not want to obey do not keep the Sabbath, and obeying is linked to the rest of God.
Heb 4: 6 Therefore, since it remains for some to enter it, and that those to whom the good news was previously preached did not enter because of disobedience,
God's Rest, and the Sabbath are linked and are foundations of the heart of man. If the Sabbath is a holy day, and blessed, holy for being dedicated to the works of God, and blessed for bringing joy and peace, then the connection of man's heart to God's heart generates obedience out of love, and obedience out of love love leads to imitating God, and the most like God receives salvation. All things are connected and none of them canceled.