Or HaChaim on Exodus 20:10/אור החיים על שמות כ׳:י׳

1 ויום השביעי שבת, "and the seventh day is Sabbath, etc." The verse means that "by observing the seventh day as Sabbath you confirm that the Lord is your G'd." This is why Shemot Rabbah 25 describes the Sabbath as equal to the entire Torah in importance. Perhaps there is another allusion in the very word שבת which suggests that it is equal to the entire Torah. We know that the commandments which the Israelites heard from the mouth of Moses totalled 611. The other two commandments i.e. the first two of the Ten Commandments they heard directly from the mouth of G'd. The first of these was a positive commandment, the second a negative one. We know that the positive commandments are perceived as originating with the attribute of Mercy seeing it is these for which we receive a reward. The negative commandments are perceived as originating with the attribute of Justice, seeing violation results in punishment. When you look at the numerical value of the tetragram י־ה־ו־ה plus the name א־ד־נ־י you obtain a total of 91. When you add 611, i.e. the commandments Israel received through an intermediary you get the numerical value of the word שבת, =702.

2We also have a statement in Shabbat 118 that if someone observes the Sabbath meticulously his sins will be forgiven even if they included idolatry of the type Enosh was guilty of. When the Torah writes: "and the seventh day will be Sabbath for the Lord your G'd," the word "your G'd" must be understood as "the G'd who is your exclusive G'd," i.e. you have thereby indicated that you have accepted Him as your only G'd. This is derived from reading the words: ויום השביעי שבת לשם אלוקיך, "and on the seventh day you demonstrate by keeping the Sabbath that you are committed only to the Lord your G'd."

3The words שבת לשם are to teach us that if one observes the Sabbath as a day on which one recharges one's physical batteries, this is not what the Sabbath is all about. Unless one demonstrates that the Sabbath is the day of the Lord, one has not observed it in the true meaning of the word.

4The conjunctive letter ו which connects the words תעבוד ויום השביעי suggests that far from not having any work to perform on the Sabbath, you are to perform work of a different nature. On that day the work you perform is for G'd instead of for yourself. Only מלאכתך, your work, is not to be done on that day.