Preaching no more than what the Bible says

"The second text is Matthew 23:2-3, where the Lord says, 'The scribes and Pharisees sit in Moses' seat; so practice and observe whatever they tell you.'
'Here, here,' they say, 'we have authority to teach what we think to be right.'
I reply: if that is what Christ means, then we are in a sorry plight. Then every pope might create more new laws, until the world could no longer contain them all. But they treat this text just like the previous one. What does it mean to sit in Moses' seat? Let us ask, what did Moses teach? And if he were still sitting in his seat today, what would he be teaching? Beyond a doubt, nothing but what he taught of old, namely, the commandments and word of God. He has never yet uttered any doctrine of men. Rather as almost every chapter shows, he spoke what God commanded him to speak.
It follows, then, that he who teaches something different from Moses does not sit in Moses' seat. For the Lord calls it Moses' seat, because from it the doctrine of Moses should be spoken and taught. The same meaning is contained in the words which follow, where the Lord says, 'But do not do what they do; for they preach, but do not practice. For they bind heavy burdens, hard to bear, and lay them on men's shoulders; but they themselves will not move them with their finger' [Matt. 23:3-4].
See, here he takes their works to task, because they lay many laws beyond the doctrines of Moses on men's shoulders, laws which they themselves will not touch. And afterward he says, 'Woe to you, scribes and Pharisees, hypocrites! who say, 'If anyone swears by the temple, it is nothing; but if anyone sears by the gold of the temple, he is bound by his oath.' You blind fools. For which is greater, the gold or the temple that has made the gold sacred?' [Matt. 23:16-17]. Is it not clear enough here that Christ condemns their man-made doctrines? He can, therefore, not have sanctioned them by speaking of sitting in Moses' seat; else he would have  contradicted himself. Therefore Moses' seat must mean no more than the law of Moses, and the sitting in it no more than the preaching of the law of Moses." - Martin Luther, Avoiding the Doctrines of Men, Pg. 224 - 225