Bereishit / Genesis
Genesis 2:1-3
God completes creation in six days and rests on the seventh, blessing and sanctifying it — establishing the seven-day week as rooted in the structure of creation itself.
וַיְכַ֤ל אֱלֹהִים֙ בַּיּ֣וֹם הַשְּׁבִיעִ֔י מְלַאכְתּ֖וֹ אֲשֶׁ֣ר עָשָׂ֑ה וַיִּשְׁבֹּת֙ בַּיּ֣וֹם הַשְּׁבִיעִ֔י מִכׇּל־מְלַאכְתּ֖וֹ אֲשֶׁ֥ר עָשָֽׂה׃ וַיְבָ֤רֶךְ אֱלֹהִים֙ אֶת־י֣וֹם הַשְּׁבִיעִ֔י וַיְקַדֵּ֖שׁ אֹת֑וֹ כִּ֣י ב֤וֹ שָׁבַת֙ מִכׇּל־מְלַאכְתּ֔וֹ אֲשֶׁר־בָּרָ֥א אֱלֹהִ֖ים לַעֲשֽׂוֹת׃ {פ}
On the seventh day God finished the work that had been undertaken, ceasing on the seventh day from doing any of the work. And God blessed the seventh day and declared it holy—having ceased on it from all the work of creation that God had done.
Why it matters — The foundational biblical source for the seven-day week: six days of creative activity followed by Shabbat as the cosmic seventh.