(א) בָּרוּךְ אַתָּה יְהֹוָה אֱלֹהֵֽינוּ מֶֽלֶךְ הָעוֹלָם אֲשֶׁר קִדְּ֒שָֽׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ לַעֲסֹק בְּדִבְרֵי תוֹרָה:
(1) Blessed are You, Adonoy our God, Ruler of the Universe, Who sanctified us with commandments and commanded us to be engrossed in the words of Torah.
(8) Remember the sabbath day and keep it holy. (9) Six days you shall labor and do all your work, (10) but the seventh day is a sabbath of Hashem: you shall not do any work—you, your son or daughter, your male or female slave, or your cattle, or the stranger who is within your settlements. (11) For in six days Hashem made heaven and earth and sea, and all that is in them, and They rested on the seventh day; therefore Hashem blessed the sabbath day and hallowed it.
(12) Observe the sabbath day and keep it holy, as Hashem your God has commanded you. (13) Six days you shall labor and do all your work, (14) but the seventh day is a sabbath of Hashem your God; you shall not do any work—you, your son or your daughter, your male or female slave, your ox or your ass, or any of your cattle, or the stranger in your settlements, so that your male and female slave may rest as you do. (15) Remember that you were a slave in the land of Egypt and Hashem your God freed you from there with a mighty hand and an outstretched arm; therefore Hashem your God has commanded you to observe the sabbath day.
Shamor vezahor bedibur ehad
Hishmi'anu el hamyuhad
Adonay ehad ushmo ehad
Leshem ultiferet relit-hilah
Kol Haneshamah: Shabbat Vehagim, Lehah Dodi
"Keep" and "Remember" in a sole command
the solitary God did us command
"I AM!" is one, the Name is one,
in name, in splendor, and in praise.
זכור. לְשׁוֹן פָּעוֹל הוּא, כְּמוֹ אָכוֹל וְשָׁתוֹ (ישעיהו כ"ב), הָלוֹךְ וּבָכֹה (שמואל ב ג'), וְכֵן פִּתְרוֹנוֹ: תְּנוּ לֵב לִזְכֹּר תָּמִיד אֶת יוֹם הַשַּׁבָּת, שֶׁאִם נִזְדַּמֵּן לְךָ חֵפֶץ יָפֶה תְּהֵא מַזְמִינוֹ לְשַׁבָּת (מכילתא):
זכור — This word expresses the verbal action without any reference to a particular time (the infinitive), similar to, (Isaiah 22:13) אכול ושתו “to eat and to drink”; (II Samuel 3:16) הלוך ובכה “to go and to weep”; and the following is its meaning: take care to remember always the Sabbath day — that if, for example, you come across a nice article of food during the week, put it by for the Sabbath (Beitzah 16a).
ויקדשהו, Hashem sanctified it entirely, so that the entire day be devoted to matters spiritual.
שמור OBSERVE [THE SABBATH DAY] — But in the former Ten Commandments (i.e. where they were first promulgated, in Exodus XX.), it states, “Remember [the Sabbath day]"! The explanation is: Both of them (זכור and שמור) were spoken in one utterance and as one word, and were heard in one hearing (i.e. were heard simultaneously) (Mekhilta d'Rabbi Yishmael 20:8:1).
Rabbanit Surale Rosen, "How many Shabbat candles should one light?", https://www.sefaria.org/sheets/374002.28?lang=bi&with=all&lang2=en
The primary reason cited for lighting two candles is a reflection of zachor and shamor, and not as a symbol of a man and woman. The basic halakhic obligation requires only one candle, but lighting two is an ancient and fundamental custom, “a true custom inherited from the early great scholars” (Ateret Zvi, Orah Haim 263:2).
וְיֵשׁ מְכַוְּנִים לַעֲשׂוֹת ב' פְּתִילוֹת אֶחָד כְּנֶגֶד זָכוֹר וְאֶחָד כְּנֶגֶד שָׁמוֹר.
Some specifically make two lights; one corresponding to "Zakhor" (Remember) and one corresponding to "Shamor" (Guard).
Jacob J. Staub, "A Guide to Jewish Practice: Volume 2 - Shabbat and Holidays", pages 45-46
Because of the well-known and widespread use of the term "shomer Shabbat" in the Orthodox world, non-Orthodox Jews sometimes say, "We observe Shabbat - we light candles, make Kiddush and have a meal as a family on Friday night, and we often go to synagogue, but we are not shomer Shabbat." In other words: "Shabbat occupies an important place in our week, but we do not observe Shabbat as Orthodox Jews do." When non-Orthodox Jews cede to the Orthodox the right to define the term "shomer Shabbat," we inadvertently denigrate not only the value and importance of our own ritual practice, but also our overall approach to Jewish living.
David A. Teutsch, "A Guide to Jewish Practice: Volume 2 - Shabbat and Holidays", pages 47
I believe it is helpful to use the term "shomer Shabbat" to refer to those who follow some version of the halakha regarding Shabbat observance. For that large group of Jews who take Shabbat observance seriously outside the framework of halakha, I prefer the term "zakher Shabbat." In the two versions of the Ten Commandments, one uses the term "shamor," ("observe the Sabbath"), while the other uses the term "zakhor," ("remember the Sabbath"). Using a different term indicates deep engagement with the tradition but reflects the necessarily different approach of someone making values-based decisions.
Ethan Tucker, "Shamor and Zakhor: Competing Frames for Shabbat in the Torah and Today", https://blogs.timesofisrael.com/shamor-and-zakhor-competing-frames-for-shabbat-in-the-torah-and-today/
Deeper investigation reveals that these two formulations actually represent two strong, competing visions of what Shabbat is all about: שמור/Exodus and זכור/Creation. For the שמור model, Shabbat is all about taking home the lessons of being a slave and making sure that the economically disadvantaged get a chance to rest. This rationale calls us away from the labors of the week so that we can enjoy rest and bodily rejuvenation. For the זכור model, we are called instead to experience a Shabbat world that is fully created. By imitating God’s stopping and resting, we also acknowledge that we did not create the world and therefore do not have the right to dominate it without limits. It is our day to draw close to God, not to serve our ends or to tamper with God’s handiwork.