כָּל־מְלָאכָ֖ה לֹ֣א תַעֲשׂ֑וּ חֻקַּ֤ת עוֹלָם֙ לְדֹרֹ֣תֵיכֶ֔ם בְּכֹ֖ל מֹֽשְׁבֹֽתֵיכֶֽם׃
Ye shall do no manner of work; it is a statute for ever throughout your generations in all your dwellings.
Read midrashic interpretation of Leviticus 23:31: and classical rabbinic exegesis.