'Hearts' in the Bible

do not harden your hearts as in the rebellion, in the day of testing in the wilderness,

{while it is said}, "Today, if you hear his voice, do not harden your hearts as in the rebellion."

again he ordains a certain day, today, speaking by David after so long a time, just as had been said before, "Today, if you hear his voice, do not harden your hearts."

For this [is] the covenant that I will decree with the house of Israel after those days, says the Lord: I am putting my laws in their minds and I will write them on their hearts, and I will be {their} God and they will be {my} people.

"This [is] the covenant that I will decree for them after those days, says the Lord: I am putting my laws on their hearts, and I will write them on their minds."

let us approach with a true heart in the full assurance of faith, our hearts sprinkled [clean] from an evil conscience and our bodies washed with pure water.