Q. 159. How is the Word of God to be preached by those that are called thereunto?
Westminster Larger Catechism – The Westminster Standard
A. 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.