2 Corinthians 3:2-3

The only letter of recommendation we need is you yourselves. Your lives are a letter written in our hearts; everyone can read it and recognize our good work among you. Clearly, you are a letter from Christ showing the result of our ministry among you. This “letter” is written not with pen and ink, but with the Spirit of the living God. It is carved not on tablets of stone, but on human hearts.