Exodus 31:12-17 
12And יהוה spoke to Mosheh, saying, 13And you, speak to the children of Yisra’ĕl, saying, ‘My Sabbaths you are to guard, by all means, for it is a sign between Me and you throughout your generations, to know that I, יהוה, am setting you apart. 14‘And you shall guard the Sabbath, for it is set-apart to you. Everyone who profanes it shall certainly be put to death, for anyone who does work on it, that being shall be cut off from among his people. 15‘Six days work is done, and on the seventh is a Sabbath of rest, set-apart to יהוה. Everyone doing work on the Sabbath day shall certainly be put to death. 16‘And the children of Yisra’ĕl shall guard the Sabbath, to perform the Sabbath throughout their generations as an everlasting covenant. 17‘Between Me and the children of Yisra’ĕl it is a sign forever. For in six days יהוה made the heavens and the earth, and on the seventh day He rested and was refreshed.’ ”

Not only is the Sabbath set apart and holy [H6942 qadash ~ to consecrate, sanctify, prepare, dedicate, be hallowed, be holy, be sanctified, be separate], but it is a sign between Yahweh and us, His people.  Why? What is the reason for this?
“to know that I, יהוה, am setting you apart.”
The Sabbath is the way that Yah separates us from the world.
To reject His sign is not a good thing. It is very unwise.

With regard to verses 14-15, we could fill many books with the thoughts of man on what it means to work or not work on the Sabbath. Here is what I get out of these verses:
1. We are to keep the Shabbat, because it is set apart for us.
2. Whoever profanes it shall die
3. Whoever works on Shabbat will be cut off from the people
4. We are to work six days and rest on Shabbat, the seventh day.
5. Whoever works on Shabbat will be put to death.

#1 is quite clear. Yah established the Sabbath in Genesis and He made it holy. It is not just a command given in “the law”, the Torah instructions. It is a concept from the very beginning, and it is highly important to Yahweh. He includes it as one of His appointed times (moedim) in Leviticus 23. It is listed along with the feast days as important to Him.

#2 We see in Numbers 15:30-35 that a man defiantly broke the Sabbath. His punishment was death.  Hmmm, who wants some of that? Not me.

#3 What does it mean to be “cut off from the people”? Cut off is [H3772 karath — to cut, cut off, cut down, cut off a body part, cut out, eliminate, kill, cut a covenant] We see from this definition that it is bad to be cut off. It means to be destroyed, eliminated, killed.

#4 Scripture says to work six days and rest on the seventh. This does not match our work culture, which typically works five days and is off work for two. My wife and I own a cafe, and as a result, we have been working six days a week for eleven years!! Way before we learned Torah.
Can modern day employment or operating a business be compared to the “work” of these people back in the day? Their work was to care for livestock, care for children/wives, maintain their dwelling, obtain water, move as directed by Yah. I don’t know if our modern situation can be considered equivalent. Either way, Tracy and I work six days and honor Shabbat on the seventh day.

#5 In their Torah community, offenders were put to death. We are now in exile. We are not living within the community of Yahweh. We are scattered among the nations, and we are subject to the laws of the nations. If I took a member of my Torah fellowship outside and stoned him to death for working on Shabbat, things would not go well for me. I believe this was enforced when Israel was not scattered, and lived in community, under the kingship of Yah. Scripture says there will be a second exodus, greater than the first (Jeremiah 16, among other references). I think there will be another time, before the end when all is fulfilled, that the people of Yahweh will be gathered and placed into community. I have no doubt that Yah’s instructions will be implemented in that community.