Verily, my sabbaths ye shall keep— As the precept of observing the sabbath has been so strongly enjoined before, it seems reasonable to conclude, that the repetition in this place has reference only to the workmen, and the work of the tabernacle; which, the Lord here informs them, is not to break in upon their observation of that great and important duty: and, accordingly, he adds, Exodus 31:14 whosoever doth any work therein, (even of this sacred sort, for the furnishing of the tabernacle,) that soul shall be cut off from among his people. See also Exodus 31:15. Understanding the precept in this view, their version seems to be just, who would read, nevertheless my sabbaths ye shall keep, to make it known, that I, Jehovah, have sanctified you: i.e. "separated you from all the world to be my peculiar people."
For it is a sign between me and you— In Exodus 31:17 it is said, It is a sign between me and the children of Israel for ever, for in six days, &c. "The meaning of which," says Hallet, "seems plainly to be this: that, as the sabbath was appointed in memory of God's having finished the work of creation in six days, and of his having rested on the seventh; so the Jews, by observing this sabbath, did testify their belief in the Creator of heaven and earth; and profess themselves to be the servants and worshippers of the true God, in opposition to the idols who made not the heaven and earth: at the same time the idolatrous nation of Egypt, from which the Israelites were delivered, and the other idolatrous nations which lived around them, had renounced the worship of the true God, and so would not observe his sabbath. The observation of the sabbath, therefore, was a sign that men were not idolaters, but worshippers of the true God. As it was appointed at the beginning of the world, it was appointed for all mankind. And it would equally serve for a sign between God and any other nation, as between God and the Hebrews; provided any other nation had kept the sabbath, that other nation would hereby have been as much proved by this sign to be worshippers of the true God, and as much distinguished from their idolatrous neighbours, as the Hebrews hereby were. But the truth is, all other nations had forsaken the worship of God, and apostatized to idolatry; and only the Jewish nation adhered to him. To be a standing evidence that they did adhere to him, God ordered them to continue to observe the sabbath; from the observation whereof other nations were gone astray: the solemn worship of God on which day would more strongly be a sign that they were not idolaters, than their mere resting from their labours could be." See more in Hallet, vol. 3: p. 115. Poole observes, that "the sabbath was a five-fold sign: first, Commemorative, of God's creation of and dominion over the Israelites, and all other things; to whom they do hereby profess their subjection. 2nd, Indicative, shewing, that they were made to be holy; and that their sanctification can be had from none but God, as it here follows, and from the observation of his days and appointments. 3rdly, Distinctive, whereby they owned themselves to be the Lord's peculiar people, by a religious keeping of those sabbaths which the rest of the world grossly neglected and profanely scoffed at. 4thly, Prefigurative, of that rest which Christ should purchase for them; to wit, a rest from the burden of the ceremonial, and from the curses and rigours of the moral law; as also from sin, and the wrath of God for ever. See Hebrews 4:4-5." "And 5thly, Confirmative, both assuring them of God's good will towards them; and that, as he blessed the sabbath, so he would bless them in the holy use of it, with temporal, spiritual, and everlasting blessings, as he declares in many places of Scripture: and assuring God of their standing to that covenant made between God and them; so that this was a mutual stipulation or ratification of the covenant of grace on both sides."