'Heart' in the Bible

Paul, Silvanus (Silas), and Timothy,To the church of the Thessalonians in God the Father and the Lord Jesus Christ: Grace to you and peace [inner calm and spiritual well-being from God].

For our witness does not come from error or from an unclean heart or from deceit:

But we, brethren, being taken from you for a short time in presence, not in heart, endeavoured the more abundantly to see your face with great desire.

And last of all, the prayer which we make to you from our heart and in the name of the Lord Jesus, is this: that as we made clear to you what sort of behaviour is pleasing to God, as in fact you are doing now, so you will go on in these ways, but more and more.