שִׁבְעַ֣ת יָמִ֔ים תַּקְרִ֥יבוּ אִשֶּׁ֖ה לַיהוָ֑ה בַּיּ֣וֹם הַשְּׁמִינִ֡י מִקְרָא־קֹדֶשׁ֩ יִהְיֶ֨ה לָכֶ֜ם וְהִקְרַבְתֶּ֨ם אִשֶּׁ֤ה לַֽיהוָה֙ עֲצֶ֣רֶת הִ֔וא כָּל־מְלֶ֥אכֶת עֲבֹדָ֖ה לֹ֥א תַעֲשֽׂוּ׃
Seven days ye shall bring an offering made by fire unto the LORD; on the eighth day shall be a holy convocation unto you; and ye shall bring an offering made by fire unto the LORD; it is a day of solemn assembly; ye shall do no manner of servile work.
Read kabbalistic (mystical) interpretation of Leviticus 23:36: and classical mystical sources.