II Corinthians 3:2-5

You are our epistle written in our hearts, known and read by all men; clearly you are an epistle of Christ, ministered by us, written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets of flesh, that is, of the heart. And we have such trust through Christ toward God. Not that we are sufficient of ourselves to think of anything as being from ourselves, but our sufficiency is from God