In the two versions of the Ten Commandments, the Torah stated two different commands about Shabbat: “Remember the Sabbath day, to keep it holy” (Exodus 20:8), and: “Observe the Sabbath day, to keep it holy” (Deuteronomy 5:12). From these commands, the Sages derived several halakhot related to the remembrance of Shabbat and the special place that it should be accorded.

“Remember” and “observe:” Remember it before it begins and observe it after it ends. From here the Sages said that one adds from the profane to the sacred…

Elazar ben Hananya ben Hizkiyya ben Hananya ben Garon says: “Remember the Sabbath day, to keep it holy” (Exodus 20:8); one should remember it from the first day of the week; if you happen across a fine portion you should prepare it for the sake of Shabbat.

Rabbi Yitzhak says: One should not count in the manner that others count days, but rather one should count for the sake of Shabbat.

“To keep it holy”; to sanctify it with a blessing. From here they said: One sanctifies it over wine at its start. (Mekhilta deRabbi Yishmael, Yitro, Mesekhta deBaĥodesh 7)