וְהָי֞וּ הַדְּבָרִ֣ים הָאֵ֗לֶּה אֲשֶׁ֨ר אָנֹכִ֧י מְצַוְּךָ֛ הַיּ֖וֹם עַל־לְבָבֶֽךָ׃
And these words, which I command thee this day, shall be upon thy heart;
Read kabbalistic (mystical) interpretation of Deuteronomy 6:6: and classical mystical sources.