'Take heed to yourselves, lest your example contradict your doctrine, and lest you lay such stumbling-blocks before the blind, as may be the occasion of their ruin; lest you unsay with your lives, what you say with your tongues; and be the greatest hinderers of the success of your own labours. It much hindereth our work, when other men are all the week long contradicting to poor people in private, that which we have been speaking to them from the Word of God in public, because we cannot be at hand to expose their folly; but it will much more hinder your work, if you contradict yourselves, and if your actions give your tongue the lie, and if you build up an hour or two with your mouths, and all the week after pull down with your hands! This is the way to make men think the Word of God is but idle tale, and to make preaching seem no better than prating. One proud, surly, lordly word, one needless contention, one covetous action, may cut the throat of many a sermon, and blast the fruit of all that you have been doing.'
Richard Baxter, The Reformed Pastor, p.63.