שָׁמ֣֛וֹר אֶת־י֥וֹם֩ הַשַׁבָּ֖֨ת לְקַדְּשׁ֑֜וֹ כַּאֲשֶׁ֥ר צִוְּךָ֖֣ ׀ יְהוָ֥֣ה אֱלֹהֶֽ֗יךָ
Observe the sabbath day, to keep it holy, as the LORD thy God commanded thee.
Read kabbalistic (mystical) interpretation of Deuteronomy 5:12: and classical mystical sources.