Deuteronomy 4:29 Kabbalah

וּבִקַּשְׁתֶּ֥ם מִשָּׁ֛ם אֶת־יְהוָ֥ה אֱלֹהֶ֖יךָ וּמָצָ֑אתָ כִּ֣י תִדְרְשֶׁ֔נּוּ בְּכָל־לְבָבְךָ֖ וּבְכָל־נַפְשֶֽׁךָ׃

But from thence ye will seek the LORD thy God; and thou shalt find Him, if thou search after Him with all thy heart and with all thy soul.

Read kabbalistic (mystical) interpretation of Deuteronomy 4:29: and classical mystical sources.