וַיַּעֲשׂ֣וּ בְנֵֽי־יִ֠שְׂרָאֵל הַנִּמְצְאִ֨ים בִּירוּשָׁלִַ֜ם אֶת־חַ֧ג הַמַּצּ֛וֹת שִׁבְעַ֥ת יָמִ֖ים בְּשִׂמְחָ֣ה גְדוֹלָ֑ה וּֽמְהַלְלִ֣ים לַ֠יהוָה י֣וֹם ׀ בְּי֞וֹם הַלְוִיִּ֧ם וְהַכֹּהֲנִ֛ים בִּכְלֵי־עֹ֖ז לַיהוָֽה׃ (ס)
And the children of Israel that were present at Jerusalem kept the feast of unleavened bread seven days with great gladness; and the Levites and the priests praised the LORD day by day, singing with loud instruments unto the LORD.
Read Kabbalistic (mystical) interpretations of II Chronicles 30:21: Zohar and classical Jewish mystical sources, free online.