וַיֹּ֨אמֶר יְהוָ֤ה אֶל־מֹשֶׁה֙ לֵ֣ךְ אֶל־הָעָ֔ם וְקִדַּשְׁתָּ֥ם הַיּ֖וֹם וּמָחָ֑ר וְכִבְּס֖וּ שִׂמְלֹתָֽם׃
And the LORD said unto Moses: ‘Go unto the people, and sanctify them to-day and to-morrow, and let them wash their garments,
Read kabbalistic (mystical) interpretation of Exodus 19:10: and classical mystical sources.