(8) Remember the sabbath day, to keep it holy...
(יב) שָׁמ֣֛וֹר אֶת־י֥וֹם֩ הַשַׁבָּ֖֨ת לְקַדְּשׁ֑֜וֹ
(12) Guard the sabbath day to keep it holy...
זכור: זכור ושמור בדבור אחד נאמרו.
Rashi on Exodus 20:8
"Remember:" Heb. זָכוֹר [The words] “remember (זָכוֹר)” and “keep (שָׁמוֹר)” (Deut. 5:12) were pronounced with one utterance.
שָׁמוֹר וְזָכוֹר בְּדִבּוּר אֶחָד, הִשְמִיעָֽנוּ אֵ-ל הַמְּיֻחָד.
from L'cha Dodi
"Shamor" (Guard) and "Zachor" (Remember) in one utterance -- this is what G-d uniquely was able to cause us to hear.
(ח) זָכ֛וֹר֩ אֶת־י֥֨וֹם הַשַּׁבָּ֖֜ת לְקַדְּשֽׁ֗וֹ (ט) שֵׁ֤֣שֶׁת יָמִ֣ים֙ תַּֽעֲבֹ֔ד֮ וְעָשִׂ֖֣יתָ כָּל־מְלַאכְתֶּֽךָ֒ (י) וְי֙וֹם֙ הַשְּׁבִיעִ֔֜י שַׁבָּ֖֣ת ׀ ה` אֱ-לֹהֶ֑֗יךָ לֹֽ֣א־תַעֲשֶׂ֣֨ה כָל־מְלָאכָ֡֜ה ... (יא) כִּ֣י שֵֽׁשֶׁת־יָמִים֩ עָשָׂ֨ה יְהוָ֜ה אֶת־הַשָּׁמַ֣יִם וְאֶת־הָאָ֗רֶץ אֶת־הַיָּם֙ וְאֶת־כָּל־אֲשֶׁר־בָּ֔ם וַיָּ֖נַח בַּיּ֣וֹם הַשְּׁבִיעִ֑י עַל־כֵּ֗ן בֵּרַ֧ךְ יְהוָ֛ה אֶת־י֥וֹם הַשַּׁבָּ֖ת וַֽיְקַדְּשֵֽׁהוּ׃
(8) Remember the sabbath day, to keep it holy. (9) Six days shall you labor and do all your work; (10) but the seventh day is a sabbath unto the LORD your G-d, on it don't do any manner of work... (11) for in six days the LORD made heaven and earth, the sea, and all that in them is, and rested on the seventh day; wherefore the LORD blessed the sabbath day, and made it holy.
(יב) שָׁמ֣֛וֹר אֶת־י֥וֹם֩ הַשַׁבָּ֖֨ת לְקַדְּשׁ֑֜וֹ כַּאֲשֶׁ֥ר צִוְּךָ֖֣ ׀ ה` אֱ-לֹהֶֽ֗יךָ (יג) שֵׁ֤֣שֶׁת יָמִ֣ים֙ תַּֽעֲבֹ֔ד֮ וְעָשִׂ֖֣יתָ כָּֿל־מְלַאכְתֶּֽךָ֒׃ (יד) וְי֙וֹם֙ הַשְּׁבִיעִ֜֔י שַׁבָּ֖֣ת ׀ לַה`אֱ-לֹהֶ֑֗יךָ לֹ֣א תַעֲשֶׂ֣ה כָל־מְלָאכָ֡ה... (טו) וְזָכַרְתָּ֞֗ כִּ֣י־עֶ֤֥בֶד הָיִ֣֙יתָ֙ ׀ בְּאֶ֣רֶץ מִצְרַ֔֗יִם וַיֹּצִ֨אֲךָ֜֩ יְהוָ֤֨ה אֱלֹהֶ֤֙יךָ֙ מִשָּׁ֔ם֙ בְּיָ֤֥ד חֲזָקָ֖ה֙ וּבִזְרֹ֣עַ נְטוּיָ֑֔ה עַל־כֵּ֗ן צִוְּךָ֙ יְהוָ֣ה אֱלֹהֶ֔יךָ לַעֲשׂ֖וֹת אֶת־י֥וֹם הַשַׁבָּֽת׃
(12) Observe the sabbath day, to keep it holy, as the LORD your G-d commanded thee. (13) Six days you will labor, and do all your work; (14) but the seventh day is a sabbath unto the LORD your G-d, on it don't do any manner of work.... (15) And remember that you were a slave in the land of Egypt, and the LORD your G-d brought you out with a mighty hand and an outstretched arm; therefore the LORD your G-d commanded you to keep the sabbath day.
וְשַׁבָּת קָדְשׁוֹ בְּאַהֲבָה וּבְרָצוֹן הִנְחִילָנוּ,
זִכָּרוֹן לְמַעֲשֵׂה בְרֵאשִׁית.
כִּי הוּא יוֹם תְּחִלָּה לְמִקְרָאֵי קֹדֶשׁ
זֵכֶר לִיצִיאַת מִצְרָיִם.
from the Friday Night Kiddush
...the holy Sabbath was given to with love and desire that it be an inheritance for us, a reminder of the Works of Creation. [Shabbat] is the most primary of the holy festivals, a reminder of being brought out of Egypt.