'Hearts' in the Bible

Wherefore then do ye harden your hearts, as the Egyptians and Pharaoh hardened their hearts? when he had wrought wonderfully among them, did they not let the people go, and they departed?

And Samuel spake unto all the house of Israel, saying, If ye do return unto the LORD with all your hearts, then put away the strange gods and Ashtaroth from among you, and prepare your hearts unto the LORD, and serve him only: and he will deliver you out of the hand of the Philistines.

And Saul also went home to Gibeah; and there went with him a band of men, whose hearts God had touched.

And David was greatly troubled; for the people were talking of stoning him, because their hearts were bitter, every man sorrowing for his sons and his daughters: but David made himself strong in the Lord his God.