This portion from the Diet of Speyer (1529) powerfully articulates the idea of sola scriptura and what it means for preaching. May we continue to have, nurture and celebrate such preaching.
There is, we affirm, no sure preaching or doctrine but that which abides by the word of God. According to God’s command, no other doctrine should be preached. Each text of the holy and divine Scriptures should be elucidated and explained by other texts. This holy book is in all things necessary for the Christian; it shines clearly in its own light, and is found to enlighten the darkness. We are determined by God’s grace and aid to abide in God’s Word alone, the holy gospel contained in the biblical books of the Old and New Testaments. This world alone should be preached, and nothing that is contrary to it. It is the only Truth. It is the sure rule of all Christian doctrine and conduct. It can never fail us or deceive us. Whosoever builds and abides on this foundation shall stand against all the gates of hell while all merely human additions and vanities set up against it must fall before the presence of God.
(cited in Timothy George, Reading Scriptures with the Reformers, 118-19).