What did the 4th commandment mean to the Israelites to whom it was given?

The fourth commandment was to be observed as a sign of the Mosaic Covenant the Israelites had just entered:

Exodus 31:12 And the LORD said to Moses, 13 “You are to speak to the people of Israel and say, ‘Above all you shall keep my Sabbaths, for this is a sign between me and you throughout your generations, that you may know that I, the LORD, sanctify you.

Ezekiel 20:9 But I acted for the sake of my name, that it should not be profaned in the sight of the nations among whom they lived, in whose sight I made myself known to them in bringing them out of the land of Egypt. 10 So I led them out of the land of Egypt and brought them into the wilderness. 11 I gave them my statutes and made known to them my rules, by which, if a person does them, he shall live. 12 Moreover, I gave them my Sabbaths, as a sign between me and them, that they might know that I am the LORD who sanctifies them… 19 I am the LORD your God; walk in my statutes, and be careful to obey my rules, 20 and keep my Sabbaths holy that they may be a sign between me and you, that you may know that I am the LORD your God.

Sabbath observance was to remind Israel that they were in covenant relationship with Yahweh. The reason the sign was a day of rest was to remind them that Yahweh redeemed them from the house of bondage and gave them rest.

Deut. 5:12 “‘Observe the Sabbath day, to keep it holy, as the LORD your God commanded you. 13 Six days you shall labor and do all your work, 14 but the seventh day is a Sabbath to the LORD your God. On it you shall not do any work, you or your son or your daughter or your male servant or your female servant, or your ox or your donkey or any of your livestock, or the sojourner who is within your gates, that your male servant and your female servant may rest as well as you. 15 You shall remember that you were a slave in the land of Egypt, and the LORD your God brought you out from there with a mighty hand and an outstretched arm. Therefore the LORD your God commanded you to keep the Sabbath day.

They practiced this command because they were a redeemed-by-Yahweh-people. This is what the Sabbath in the Decalouge, in the Mosaic Covenant, is about. This is not a natural law matter written on all human consciences. It’s a redemptive revelation revealed in the “gospel” in the law – God giving His people rest and rolling back the curse.

None of the Israelite observance was applicable to non covenant members, i.e. Gentiles. Actually it would be a misuse of the command for Gentiles to practice this Sabbath as if they were one of Yahweh’s people; much like an unbeliever practicing the Lord’s Supper in our day.

*The WCF/LBCF sabbatarian needs to show that 1) Non covenant members were required to keep the 4th commandment and 2) when they do keep it, keeping it means something different for them from what it means for covenant members.