וַיֵּ֧רֶד מֹשֶׁ֛ה מִן־הָהָ֖ר אֶל־הָעָ֑ם וַיְקַדֵּשׁ֙ אֶת־הָעָ֔ם וַֽיְכַבְּס֖וּ שִׂמְלֹתָֽם׃
And Moses went down from the mount unto the people, and sanctified the people; and they washed their garments.
Read kabbalistic (mystical) interpretation of Exodus 19:14: and classical mystical sources.