Albert Barnes Commentary Exodus 31:12-17

"And Jehovah spake unto Moses, saying, Speak thou also unto the children of Israel, saying, Verily ye shall keep my sabbaths: for it is a sign between me and you throughout your generations; that ye may know that I am Jehovah who sanctifieth you. Ye shall keep the sabbath therefore; for it is holy unto you: every one that profaneth it shall surely be put to death; for whosoever doeth any work therein, that soul shall be cut off from among his people. Six days shall work be done, but on the seventh day is a sabbath of solemn rest, holy to Jehovah: whosoever doeth any work on the sabbath day, he shall surely be put to death. Wherefore the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant. It is a sign between me and the children of Israel for ever: for in six days Jehovah made heaven and earth, and on the seventh day he rested, and was refreshed." — Exodus 31:12-17 (ASV)

The penal law of the Sabbath is detailed in Exodus 35:2-3. In the fourth commandment, the injunction to observe the seventh day is addressed to the conscience of the people (see Exodus 20:8 note). In this passage (Exodus 35:2–3), the object is to declare an infraction of the commandment a capital offence. The two passages (Exodus 20:8 and Exodus 35:2-3) stand in a relation to each other similar to that between Leviticus 18, Leviticus 19, and Leviticus 20. It seems likely that the penal edict was especially introduced as a caution in reference to the construction of the tabernacle, lest the people, in their zeal to carry on the work, should be tempted to break the divine law for the observance of the day.

Exodus 31:14 further clarifies this penal aspect. . The distinction between the meaning of the two expressions, to be cut off from the people, and to be put to death, is indicated here. One who was cut off from the people had, by his offence, put himself out of the terms of the covenant and was an outlaw. For such individuals, and for such alone, when the offence was one that affected the well-being of the nation, as it was in this case, death could be inflicted by the public authority.

In Exodus 31:17, it is said that on the seventh day, God rested and was refreshed. This phrase literally means “he took breath.” (2 Samuel 16:14). The application of this word to the Creator, which occurs nowhere else in Scripture, is remarkable.