Reference for Leviticus 23:41

וְחַגֹּתֶ֤ם אֹתוֹ֙ חַ֣ג לַֽיהוָ֔ה שִׁבְעַ֥ת יָמִ֖ים בַּשָּׁנָ֑ה חֻקַּ֤ת עוֹלָם֙ לְדֹרֹ֣תֵיכֶ֔ם בַּחֹ֥דֶשׁ הַשְּׁבִיעִ֖י תָּחֹ֥גּוּ אֹתֽוֹ׃

And ye shall keep it a feast unto the LORD seven days in the year; it is a statute for ever in your generations; ye shall keep it in the seventh month.