'Hearts' in the Bible

So get rid of all uncleanness and all that remains of wickedness, and with a humble spirit receive the word [of God] which is implanted [actually rooted in your heart], which is able to save your souls.

is it not plain that in your hearts you have little faith, seeing that you have become judges full of wrong thoughts?

But if ye have bitter envying and strife in your hearts, glory not, and lie not against the truth.

You are jealous and covet [what others have] and your lust goes unfulfilled; so you murder. You are envious and cannot obtain [the object of your envy]; so you fight and battle. You do not have because you do not ask [it of God].

Or does it seem to you that it is for nothing that the holy Writings say, The spirit which God put into our hearts has a strong desire for us?

Draw nigh to God, and he will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded.

Ye have lived in pleasure on the earth, and been wanton; ye have nourished your hearts, as in a day of slaughter.

Be ye also patient; stablish your hearts: for the coming of the Lord draweth nigh.