The keeping and right managing of the heart in every condition is the great business of the Christian's life. ---- John Flavel
And you shall love the LORD your God with all your heart, and with all your soul, and with all your might. And these words, which I command you this day, shall be in your heart (Deuteronomy 6:5-6).
The LORD is nigh unto those who are of a broken heart; and saves those who are of a contrite spirit. (Psalm 34:18).
Keep your heart with all diligence; for out of it are the issues of life (Proverbs 4:23).
My heart is fixed, O God, my heart is fixed; I will sing and give praise (Psalm 112:7)
Since we live by the Spirit, let us keep in step with the Spirit (Galatians 5:25).
A hymn to read, sing, play, hum, or whistle, to the glory of God: Spirit of God, Descend upon My Heart (George Croly, 1854).