'Heart' in the Bible

Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.

Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.

For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.

Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.

Be not carried about with divers and strange doctrines. For it is a good thing that the heart be established with grace; not with meats, which have not profited them that have been occupied therein.