וְעִמָּהֶם֩ הֵימָ֨ן וִֽידוּת֜וּן חֲצֹצְר֤וֹת וּמְצִלְתַּ֙יִם֙ לְמַשְׁמִיעִ֔ים וּכְלֵ֖י שִׁ֣יר הָאֱלֹהִ֑ים וּבְנֵ֥י יְדוּת֖וּן לַשָּֽׁעַר׃
and with them Heman and Jeduthun, to sound aloud with trumpets and cymbals, and with instruments for the songs of God; and the sons of Jeduthun to be at the gate.
Read kabbalistic (mystical) interpretation of I Chronicles 16:42: and classical mystical sources.