In the first epistle Paul ever wrote, he was "the least of all apostles."
He later wrote to the Ephesians that he was "less than the least of all the saints."
Shortly before his death he wrote to Timothy, "I am the chief of sinners."
Romans 7:24-25 ... O wretched man that I am! who shall deliver me from the body of this death? I thank God through Jesus Christ our Lord. So then with the mind I myself serve the law of God; but with the flesh the law of sin.