Thomas Boston wrote this in 1699, and it is as true now as ever. Failure to pray through a sermon is failure to preach well:
“(1.) That thou mayst have a word from the Lord to deliver unto them; that thou mayst not preach to them the product of thy own wisdom, and that which merely flows from thy reason; for this is poor heartless preaching.
(2.) That thy soul may be affected with the case of the people to whom thou preachest. If that be wanting, it will be tongue preaching, but not heart-preaching.
(3.) That thy heart may be inflamed with zeal for the glory of thy Master; that out of love to God, and love to souls thy preaching may flow.
(4.) That the Lord may preach it into thy own heart, both when thou studiest and deliverest it. For if this be not, thou shalt be like one that feeds others, but starves himself for hunger; or like a way-mark, that shews the way to men, but never moves a foot itself.
(5.) That thou mayst be helped to deliver it; and that, (1.) With a suitable frame, thy heart being affected with what thou speakest; (2.) Faithfully, keeping up nothing that the Lord gives thee; and, (3.) Without confusion of mind, or fear of man.
(6.) That thou mayst have bodily strength allowed for the work, that thy indisposition disturb thee not.
Lastly, That God would countenance thee in the work with his presence and power in ordinances, to make the word spoken a convincing and converting word to them that are out of Christ; a healing word to the broken; confirming to the weak, doubting and staggering ones, &c.; that God himself would drive the fish into the net, when thou spreadest it out. In a word, that thou mayst be helped to approve thyself to God, as a workman that needeth not to be ashamed, rightly dividing the word of truth.”
Thomas Boston, The Whole Works of Thomas Boston: A Soliloquy on the Art of Man-Fishing, ed. Samuel M‘Millan, vol. 5 (Aberdeen: George and Robert King, 1849), 34–35.