נָ֘כ֤וֹן לִבִּ֣י אֱ֭לֹהִים נָכ֣וֹן לִבִּ֑י אָ֝שִׁ֗ירָה וַאֲזַמֵּֽרָה׃
My heart is stedfast, O God, my heart is stedfast; I will sing, yea, I will sing praises.
Read kabbalistic (mystical) interpretation of Psalms 57:8: and classical mystical sources.