וְהַלְוִיִּ֞ם מַחְשִׁ֤ים לְכָל־הָעָם֙ לֵאמֹ֣ר הַ֔סּוּ כִּ֥י הַיּ֖וֹם קָדֹ֑שׁ וְאַל־תֵּעָצֵֽבוּ׃
So the Levites stilled all the people, saying: ‘Hold your peace, for the day is holy; neither be ye grieved.’
Read kabbalistic (mystical) interpretation of Nehemiah 8:11: and classical mystical sources.