שַׁבַּ֨ת שַׁבָּת֥וֹן הִיא֙ לָכֶ֔ם וְעִנִּיתֶ֖ם אֶת־נַפְשֹׁתֵיכֶ֑ם חֻקַּ֖ת עוֹלָֽם׃
It is a sabbath of solemn rest unto you, and ye shall afflict your souls; it is a statute for ever.
Read kabbalistic (mystical) interpretation of Leviticus 16:31: and classical mystical sources.