Leviticus 23:36

עצרת הוא — The word is derived from the root עצר “to hold back” and suggests: I keep you back with Me one day more. It is similar to the case of a king who invited his children to a banquet for a certain number of days. When the time arrived for them to take their departure he said, “Children, I beg of you, stay one day more with me; it is so hard for me to part with you!” (cf. Rashi on Numbers 29:36 and Sukkah 55b). כל מלאכת עבדה ANY WORK THAT IS AN עבדה — i. e. even such work which rests as an obligation (עבודה) upon you because if it is left undone it involves monetary loss (cf. Rashi v. 8), לא תעשו YE SHALL NOT DO: — One might think that it is forbidden to do such urgent work (מלאכת עבדה) also on the intermediate days of Passover and Tabernacles (which are Half-festivals)! Scripture, however, states: עצרת] הוא], “it (i. e. the eighth day) forms a restriction: [ye shall do no urgent work]” — but on the intermediate days such work is not forbidden (Sifra, Emor, Section 12 6).

שִׁבְעַ֣ת יָמִ֔ים תַּקְרִ֥יבוּ אִשֶּׁ֖ה לַיהֹוָ֑ה בַּיּ֣וֹם הַשְּׁמִינִ֡י מִקְרָא־קֹ֩דֶשׁ֩ יִהְיֶ֨ה לָכֶ֜ם וְהִקְרַבְתֶּ֨ם אִשֶּׁ֤ה לַֽיהֹוָה֙ עֲצֶ֣רֶת הִ֔וא כׇּל־מְלֶ֥אכֶת עֲבֹדָ֖ה לֹ֥א תַעֲשֽׂוּ׃

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.