WLC Q.158: By whom is the word of God to be preached?
The word of God is to be preached only by such as are sufficiently gifted, (1 Tim. 3:2,6, Eph. 4:8–11, Hosea 4:6, Mal. 2:7, 2 Cor. 3:6) and also duly approved and called to that office. (Jer. 14:15, Rom. 10:15, Heb. 5:4, 1 Cor. 12:28–29, 1 Tim. 3:10, 1 Tim. 4:14, 1 Tim. 5:22)