2 Corinthians 3:3

3:3 revealing that you are a letter of Christ, delivered by us, written not with ink but by the Spirit of the living God, not on stone tablets but on tablets of human hearts.

2 Corinthians 4:6

4:6 For God, who said “Let light shine out of darkness,” is the one who shined in our hearts to give us the light of the glorious knowledge of God in the face of Christ.

2 Corinthians 7:3

7:3 I do not say this to condemn you, for I told you before that you are in our hearts so that we die together and live together with you.