ויקרא כ״ג:א׳-ג׳

דבר אל בני ישראל, מועדי ה'. עֲשֵׂה מוֹעֲדוֹת שֶׁיִּהְיוּ יִשְֹרָאֵל מְלֻמָּדִין בָּהֶם, שֶׁמְּעַבְּרִים אֶת הַשָּׁנָה עַל גָּלֻיּוֹת שֶׁנֶּעֶקְרוּ מִמְּקוֹמָן לַעֲלוֹת לָרֶגֶל וַעֲדַיִן לֹא הִגִּיעוּ לִירוּשָׁלַיִם (ספרא):

'דבר אל בני ישראל, מועדי ה‎‎ SPEAK UNTO THE CHILDREN OF ISRAEL [AND DECLARE UNTO THEM] THE APPOINTED FESTIVALS OF THE LORD — This means, Regulate the festive seasons in such a manner that all Israel should become practised in them (their observance). Hence we derive the law that they (the Sanhedrin) proclaim a leap-year (i. e. intercalate a second Adar) for the sake of those living in the diaspora who have already left their homes in order to go up for the festival but have not yet arrived in Jerusalem (Sifra, Emor, Section 9 1; cf. Sanhedrin 11a).

ששת ימים. מָה עִנְיַן שַׁבָּת אֵצֶל מוֹעֲדוֹת? לְלַמֶּדְךָ שֶׁכָּל הַמְחַלֵּל אֶת הַמּוֹעֲדוֹת מַעֲלִין עָלָיו כְּאִלּוּ חִלֵּל אֶת הַשַּׁבָּתוֹת, וְכָל הַמְקַיֵּם אֶת הַמּוֹעֲדוֹת מַעֲלִין עָלָיו כְּאִלּוּ קִיֵּם אֶת הַשַּׁבָּתוֹת (שם):

ששת ימים SIX DAYS [MAY WORK BE DONE BUT THE SEVENTH DAY IS THE SABBATH OF STRICT REST] — What relation is there between the Sabbath (the day that is invariably fixed by God as the holy day) and the festive seasons (the times of which are variable, being dependent upon the proclamation of the Sanhedrin)? But by putting both into juxtaposition Scripture intends to teach you that he who desecrates the festivals is regarded as though he had desecrated the Sabbath, and that he who keeps the festivals is regarded as though he had kept the Sabbath (Sifra, Emor, Section 9 7).