About the Sabbath

Establishing the Sabbath on the seventh day of creation

Gen 2:1  Thus the heavens and the earth were completed, and all their array.
Gen 2:2  And in the seventh day Yahweh completed His work which He had done, and He ceased on the seventh day from all His work which He had made.
Gen 2:3  And Yahweh blessed the seventh day and set it apart, because on it He ceased from all His work which Yahweh in creating had made.

When did Yahweh first specifically give instructions about recognizing the seventh day as set apart?

The first time was when the people were told not to go to gather mana on the seventh day of the week; and that Yahweh would not provide mana on that day.
Exo 16:29  “See, because יהוה has given you the Sabbath, therefore He is giving you bread for two days on the sixth day. Let each one stay in his place, do not let anyone go out of his place on the seventh day.”

Next time was  Exo 20:8  “Remember the Sabbath day, to set it apart."

How do you "set it apart?"

Exo 20:10 ...but the seventh day is a Sabbath of יהוה your Elohim. You do not do any work – you, nor your son, nor your daughter, nor your male servant, nor your female servant, nor your cattle, nor your stranger who is within your gates.

And if you believe what Paul said in Romans chapter 11 about being grafted into the Olive tree, the tree being Israel, then you are one of the "children of Israel."
Exo 31:16  ‘And the children of Yisra’ěl shall guard the Sabbath, to perform the Sabbath throughout their generations as an everlasting covenant.

How do you "guard" the Sabbath?

The word "guard" is the Hebrew word shaw-mar' שָׁמַר Strong's H8104. To watch over, guard, in the sense of protecting and preserving.
So, you guard the Sabbath by protecting it, not allowing it to be changed, or interrupted by outsiders.
Neh 10:31 ...and that if the peoples of the land bring wares or any grain to sell on the Sabbath day, we would not buy it from them on the Sabbath, or on a set-apart day...

You preserve it by meeting with others who can continue on.
Lev 23:3  ‘Six days work is done, but the seventh day is a Sabbath of rest, a set-apart gathering. You do no work, it is a Sabbath to יהוה in all your dwellings.

The Sabbath Blesses You

Lev 23:3  ‘Six days work is done, but the seventh day is a Sabbath of rest (ceasing from the distraction of laboring), a set-apart gathering.
Yahweh only asks for your total attention for one day each week; and not one hour out of one day, but one DAY.
Hearing a good teaching to get better understanding of Scripture, praise and worship with others, and fellowship on Sabbath are a blessing. Being encouraged by good teaching to study even more on your own builds up the body of Messiah and produces fruit. Done well, these things will fill up more than one day.

<>This is why Messiah said:  Mark 2:27  And He said to them, “The Sabbath was made for man, and not man for the Sabbath.
Yahweh established the Sabbath so that man could be encourged, built-up, and blessed.