The Baal HaTurim says that the pasuk of “Zachor Es Yom HaShabbos” is the seventh pasuk in the Aseres HaDibros. It also starts with the letter Zayin which has the numerical equivalent of seven.
Two pasukim later the pasuk “Ata U’Bincha U’Bitecha …” lists seven people in it. All these sevens are in honor of the seventh day Shabbos.
The pasuk of Zachor itself has five words to show that whoever keeps Shabbos it is as if he kept the entire Chamisha Chumshei Torah
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