You see, therefore, what attitude he must have whose duty it is to discharge the office of judge and sword, namely, to subdue an feelings of fear, love, favor, sympathy, greed, ambition, reputation, life, or death, and to be a simple lover of simple truth and just judgment, “Because,” said Jehoshaphat, King of Judah, “judgment is the Lord’s” (2 Chron. 19:6). A judge must bear the hatred of many; he must be in peril because of hostility and be tempted by sympathy and gain. He will not be able to overcome these shocks and stand firm unless he looks to God alone. But how will he look to God alone unless his heart is established by firm faith? Look at the examples of even the best jurists. When they either teach publicly or write, they treat of justice most excellently; but in their private counseling they think much differently and are unlike themselves. For here partiality toward persons or sympathy in view of calamity (to put the best construction on it) bends them from the course of justice, so that they seek to heal and aid, as it were, the helpless, which they did not do when they taught publicly. Because of emotion they do not see that they are bending aside from the justice which they taught publicly. So difficult, rare, and arduous a thing is a simple and straight eye in a judge.
The same is to be seen in the greatest theologians, such as Augustine and Bernard, and in their predecessors, Cyprian, Tertullian, and the like. In public they interpret the Scriptures purely and in a clean manner; but when questions are set before them, they seldom remain on the right track but take something away from Scripture, give in to the particular case or the person, and do violence to the words of God. Observe them in what they write, as they did against Arius, or Jerome against Jovinian, or Augustine against the Manichaeans, or Bernard against free will; and you will see that I speak truly. Thus none of the saints hitherto has put off the whole flesh or killed its feelings, and there is no hope other than that both judge and teacher act in the fear of God, always suspicious of themselves, lest perhaps they handle the Law of God and His Word improperly. Complacency has no room where divine and serious issues are at stake.
Luther’s works, vol. 9: Lectures on Deuteronomy 1525