Iain Murray, reflecting on the preaching ministry of Martyn Lloyd-Jones, offers this reminder (and warning) to all who preach:
The preacher's first and supreme concern has to be that his
words are an expression of the mind of God in Scripture. "If any many
speaks, let him speak as the oracles of God" (1 Pet. 4:11). The
preacher is nothing unless he is an interpreter and exegete of
revelation. Apart from that he has no right to command the attention of
his fellow men. To expect the Holy Spirit to give his aid to what are merely our ideas is to desecrate the pulpit (italics mine).
--Iain Murray, Lloyd-Jones: Messenger of Grace
Preachers, read that last sentence again and meditate on it as you prepare for this Sunday!