'Hearts' in the Bible

harden not your hearts, as in the provocation, in the day of temptation in the wilderness;

in that it is said, To-day if ye will hear his voice, do not harden your hearts, as in the provocation;

again he determines a certain day, saying, in David, 'To-day,' after so long a time; (according as it has been said before), To-day, if ye will hear his voice, harden not your hearts.

Because this is the covenant that I will covenant to the house of Israel after those days, saith the Lord: Giving my laws into their mind, I will write them also upon their hearts; and I will be to them for God, and they shall be to me for people.

This is the covenant which I will establish towards them after those days, saith the Lord: Giving my laws into their hearts, I will write them also in their understandings;

let us approach with a true heart, in full assurance of faith, sprinkled as to our hearts from a wicked conscience, and washed as to our body with pure water.