The seventh day is Shabbos (the Sabbath) to Hashem your God; don’t do any work on it… (Exodus 20:10)
The kind of work prohibited on Shabbos is called melacha, meaning creative labor. There are 39 melachos: ploughing, sowing, reaping, binding sheaves, threshing, winnowing, selecting, sifting, grinding, kneading, baking/cooking, shearing, whitening/bleaching, combing, dyeing, spinning, threading the warp of a loom, threading the heddles of a loom, weaving, separating into threads, tying a knot, untying a knot, sewing, tearing, trapping, slaughtering, skinning, tanning, smoothing, scoring, cutting, writing, erasing, building, demolishing, kindling a fire, extinguishing, completing an object, and transporting an object between domains (or through a public domain). These are the labors that were necessary for the construction of the Mishkan (Tabernacle) and they demonstrate man’s mastery. (“Melacha” shares the same root as the word “melech,” meaning a king. The other word for labor is “avodah,” sharing the same root as “eved,” a servant.)
People get confused by the obligation to “rest” on Shabbos (which we’ll come to later in Mitzvah #85, IY”H). They reason, “Isn’t driving to shul more ‘restful’ than walking a mile?” Perhaps, but the obligation isn’t to laze about on Shabbos, it’s to refrain from creative acts in recognition of the fact that God is in control. Walking may be more effort, but driving involves acts of “creative labor.” (For example, the ignition is very literally the act of lighting a fire.) It’s not effort that’s Biblically prohibited, it’s these 39 specific categories of labor.
By sitting back and letting God take the reins, we acknowledge Him as the Boss and we make ourselves more cognizant of all He has done, from creating the world in six days (ceasing on Shabbos) to freeing us from Egyptian bondage (where our labors did not cease until He rescued us). Accordingly, the two versions of the “Ten Commandments” reflect these two momentous occasions. The one here in parshas Yisro (Exodus 20) speaks of how God created the world, while the other, in parshas Va’eschanan (Deuteronomy 5), relates Shabbos to the Exodus from Egypt.
Our verse here continues to specify that we may not allow the members of our household to violate Shabbos, either. While it is important to encourage others to protect the sanctity of Shabbos, others have their own minds, so the laws of keeping Shabbos and having the members of your family keep Shabbos are quite different. (Back in Temple times, one could be executed for willful desecration of Shabbos; one would not receive any punishment whatsoever for another person’s violation of Shabbos.)
The prohibition against performing labor on Shabbos applies to both men and women, in all times and places. There’s an entire Talmudic tractate dedicated to Shabbos (called “Shabbos,” appropriately enough!), plus another discussing the laws of a Sabbath eruv (“Eruvin,” natch!). See Shabbos 73a-b, 154a-b, and Sanhedrin 66a. In the Shulchan Aruch, start in Orach Chaim 310. This is #320 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos and #6 of the 194 negative mitzvos that can be fulfilled today in the Chofetz Chaim’s Sefer HaMitzvos HaKatzar.