WLC 159: How is the Word of God to be preached by those that are called thereunto?
They that are called to labor in the ministry of the Word, are to preach sound doctrine, diligently, in season and out of season; plainly, not in the enticing words of man’s wisdom, but in demonstration of the Spirit, and of power; faithfully, making known the whole counsel of God; wisely, applying themselves to the necessities and capacities of the hearers; zealously, with fervent love to God and the souls of his people; sincerely, aiming at his glory, and their conversion, edification, and salvation.