God's Word... Written on our Hearts
You yourselves are our letter of recommendation, written on our hearts, to be known and read by all. And you show that you are a letter from Christ delivered by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of human hearts.
Such is the confidence that we have through Christ toward God.
2 Corinthians 3:2-4 (ESV)