כִּ֣י תִשְׁמַ֗ע בְּקוֹל֙ יְהוָ֣ה אֱלֹהֶ֔יךָ לִשְׁמֹ֤ר מִצְוֺתָיו֙ וְחֻקֹּתָ֔יו הַכְּתוּבָ֕ה בְּסֵ֥פֶר הַתּוֹרָ֖ה הַזֶּ֑ה כִּ֤י תָשׁוּב֙ אֶל־יְהוָ֣ה אֱלֹהֶ֔יךָ בְּכָל־לְבָבְךָ֖ וּבְכָל־נַפְשֶֽׁךָ׃ (פ)
if thou shalt hearken to the voice of the LORD thy God, to keep His commandments and His statutes which are written in this book of the law; if thou turn unto the LORD thy God with all thy heart, and with all thy soul.
Read kabbalistic (mystical) interpretation of Deuteronomy 30:10: and classical mystical sources.