Do we begin again to commend ourselves? Or do we need, as some others, epistles of commendation to you or letters of commendation from you? 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 tables of stone but on tables of flesh, that is, of the heart. (2 Corinthians 3:1-3).
3:1 Having again declared his sincerity (2:17), Paul asked if he needed a letter of commendation to back him up, as some others did. The language implies that false apostles mentioned later in this letter (11:13) had tried to gain acceptance by using such references.
3:2 You are ... written in our hearts: The Corinthians were Paul's letter of recommendation. These verses do not mean that letters of recommendation should not be used. Paul himself used such letters before his conversion (see Acts 9:1, 2) and after (see 8:22; Rom 16:1; 1 Cor 16:10; Col 4:10). In this case Paul did not need one because he already had one: the believing Corinthians and his ministry among them. Paul's love for the Corinthians was known to all who were acquainted with his ministry. One of the qualifications for ministry is love for people, both God's people and the lost.
3:3 an Epistle of Christ: Paul appealed to the Corinthians themselves for proof of his ministry's authenticity. God had changed them-an obvious matter of public record.
[THE NKJV STUDY BIBLE Second Edition].
JESUS IS LORD.