Or HaChaim on Exodus 20:8/אור החיים על שמות כ׳:ח׳

1 זכור את יום השבת לקדשו, "Remember the Sabbath day to keep it holy." The meaning is that one should remember the Sabbath from the first day of the week. The Torah mentioned the seventh day before it mentioned the six days previous to the Sabbath in order to drive home the point that the Sabbath must be uppermost in our thoughts already prior to the six days preceding it. Were this not so the Torah would have written: "perform your work during six days and remember the Sabbath day to keep it holy."

2The expression לקדשו also implies making preparation such as the sages explained in Beytzah 16 that one should prepare for the Sabbath from the first day of the week onwards.

3An additional reason why the Torah tells us to remember the Sabbath day is mentioned in Midrash Tehilim 92. Adam was created on the sixth day and sinned on that day. Along came the Sabbath and acted as advocate for Adam in front of G'd. He pleaded with G'd saying: "no human being has ever been killed; why should it fall to my lot to be the first day on which a human being is killed?" As a result of the Sabbath's plea Adam was saved from death at that time. When Adam realised this he composed this Psalm, singing the praises of the Sabbath. The Torah asks us to remember the Sabbath as the day which saved Adam's life because this fact also insured our own existence and that of all of mankind. It behooves us therefore to accord special honour to the Sabbath. The Sabbath proved to be our very life-saver. When someone experiences a miraculous escape on a certain day he will forever treat that day as special year after year on the anniversay of that event. In this instance the miracle did not only occur on the Sabbath day, but the Sabbath itself was the life-saver. It is appropriate therefore that we remember this every week. The Torah wishes us to remember that the Sabbath day is to be in a totally different category from all the other six days of the week.

4The Torah says: זכור את יום השבת, that we must remember the day by name. We sanctify the Sabbath by remembering it by name. You may appropriately translate this verse as follows: "Remember the day; what are you to remember? Sabbath." The reason that we are to sanctify it is because G'd's name is also Sabbath. Rabbi Shimon bar Yochai states in his Zohar volume 2 page 88 that the name of G'd is Sabbath. Afterwards the Torah amplifies which of the seven days of the week is called Sabbath by writing: "during six days you shall perform all your work and on the seventh day is Sabbath;" this teaches that the Sabbath is the seventh day of the week. [You will note that the word "Sabbath" did not occur in the Torah's description of the creation. Ed.]