"Search me, O God, and know my heart..." Ps 139:24
"...serve the Lord your God with all your heart..." Dt 10:12
"I will give them an undivided heart and put a new spirit in them; I will remove from them their heart of stone and give them a heart of flesh." Ez 11:19
"Only be careful, and watch yourselves closely so that you do not forget the things your eyes have seen or let them slip from your heart as long as you live." Dt. 4:9
"...circumcision is circumcision of the heart, by the Spirit, not by the written code." Ro 2:29
"The Lord saw how great man's wickedness on the earth had become, and that every inclination of the thoughts of his heart was only evil all the time." Ge 6:5
"Delight yourself in the Lord and he will give you the desires of your heart." Ps 37:4
"But the things that come out of the mouth come from the heart, and these make a man 'unclean.' For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, slander." Mt 15:19
The bible speaks about our hearts a lot.
Joseph
Stowell wrote this in
Fan the Flame (Moody, 1986) about what the bible means by "heart": "Heart is used in Scripture as the most comprehensive term for the authentic person. It is the part of our being where we desire, deliberate and decide. It has been described as 'the place of conscious and decisive spiritual activity,' 'the comprehensive term for a person as a whole; his feelings, desires, passions, thought, understanding and will,' and 'the center of a person. The place to which God turns.'"
DESIRE, DELIBERATE, DECIDE. Powerful words for the powerful concept that to thrive in the Christian life our hearts must be attuned to the Lord Jesus in the power of the Holy Spirit.
"We live from our heart." This is the opening line to Dallas Willard's book, Renovation of the Heart. Even the coldly rational and calculating Sherlock Holmes would affirm this statement. Willard contends, "...the greatest need you and I have--the greatest need of collective humanity--is renovation of the heart. That spiritual place within us from which outlook, choices, and actions come has been formed by a world away from God. Now it must be transformed."
The Psalmist knew well that what he needed most was honest self-reflection guided by God. "Search me, O God, and know my heart..."