Paul noted that the true minister does not need human endorsement because changed lives are the authentic endorsement of genuine ministry. Paul could not validate his own ministry. The certainty of a valid ministry is only from Christ.
David S. Dockery, “The Pauline Letters,” in Holman Concise Bible Commentary, ed. David S. Dockery (Nashville, TN: Broadman & Holman Publishers, 1998), 562.