In the new covenant, the things that were inherited from the old covenant receive a new meaning, a new depth, and a new flavor, if I may say so. And Shabbat is no exception. There is much to be learned about the new covenant Shabbat details in the book of Hebrews: 

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“Therefore, since a promise remains of entering His rest, let us fear lest any of you seem to have come short of it. For indeed the gospel was preached to us as well as to them; but the word which they heard did not profit them, not being mixed with faith in those who heard it”.  (Hebrews 4:1-2) 

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In Greek, the phrase “the gospel was preached to us” sounds like «ἐσμεν εὐηγγελισμένοι» (esmen euangelizomeni) – “we have received the good news”. It turns out that Israel received the Gospel, after they left Egypt! And the next verse gives us one of the most important meanings of Shabbat in the new covenant – REST. 

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“For we who have believed do enter that rest, as He has said: “So I swore in My wrath, ‘They shall not enter My rest,’” although the works were finished from the foundation of the world. For He has spoken in a certain place of the seventh day in this way: “And God rested on the seventh day from all His works”; and again in this place: “They shall not enter My rest.” Since therefore it remains that some must enter it, and those to whom it was first preached did not enter because of disobedience…” (Hebrews 4:3-6) 

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Here we see both direct and unexpected transition from the notion of rest, that the old covenant Israel did not enter after they exited the Egyptian slavery, they didn’t believe the word of God and almost all of them remained in the desert, to the seventh day or Sabbath. I don’t think it was by chance that two verses say that the first Gospel was not proclaimed by the Incarnate Lord, but it was proclaimed many centuries before to the old testament Israel even before the Sinai covenant. It was the very Gospel that was supposed to take place, if they believed. They didn’t receive it then, and whatever happened, happened. And in the first century, most Jews didn’t receive the Gospel, and whatever happened, happened.     

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Boris Grisenko, the senior rabbi of KJMC