Positive commandment · Mitzvat Aseh #167 of 613
To rest on the eighth day of the festival of Sukkot
לשבות בשמיני של חג
The verse · Vayikra 23:36
שִׁבְעַת יָמִים תַּקְרִיבוּ אִשֶּׁה לַה׳ בַּיּוֹם הַשְּׁמִינִי מִקְרָא־קֹדֶשׁ יִהְיֶה לָכֶם וְהִקְרַבְתֶּם אִשֶּׁה לַה׳ עֲצֶרֶת הִוא כׇּל־מְלֶאכֶת עֲבֹדָה לֹא תַעֲשׂוּ
“Seven days you shall offer an offering made by fire to the Lord: on the eighth day shall be a holy gathering to you; and you shall offer an offering made by fire to the Lord; it is a solemn assembly; and you shall do no servile work.”
The Rambam’s words
To rest on the eighth day of the festival of Sukkot, as [Leviticus 23:36] states: "On the eighth day, there shall be a sacred holiday."
לשבות בשמיני של חג, שנאמר: "וביום השמיני מקרא קודש" (ראה ויקרא כג,לו).
Why · Sefer HaChinuch #321
Resting from work on the eighth day of Sukkot
“It is from the roots of the commandment [that it is] in order that we think about the content of the holiday in the miracle that was done for us on it, and that we praise and laud in our thoughts the One, blessed be He, Who commanded us about it and did miracles for us at this time.”
Who & when
“And [it] is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Rest on a Holiday הלכות שביתת יום טוב