It is absolutely unethical when one is so busy communicating that he forgets to be what he teaches…
Nothing is more dangerous than to have a bunch of high-flying feelings and exalted resolutions go off in the direction of merely eloquent speaking. The whole thing then becomes an intoxication, and the deception is that it becomes a glowing mood and that they say, “he is so sincere!"
Soren Kierkergaard as quoted in Calling and Character
You, therefore, have no excuse, you who pass judgment on someone else, for at whatever point you judge the other, you are condemning yourself, because you who pass judgment do the same things. Now we know that God's judgment against those who do such things is based on truth. So when you, a mere man, pass judgment on them and yet do the same things, do you think you will escape God's judgment? Or do you show contempt for the riches of his kindness, tolerance and patience, not realizing that God's kindness leads you toward repentance?
…if you are convinced that you are a guide for the blind, a light for those who are in the dark, an instructor of the foolish, a teacher of infants, because you have in the law the embodiment of knowledge and truth-- you, then, who teach others, do you not teach yourself? You who preach against stealing, do you steal? You who say that people should not commit adultery, do you commit adultery? You who abhor idols, do you rob temples? You who brag about the law, do you dishonor God by breaking the law? As it is written: "God's name is blasphemed among the Gentiles because of you."
Romans 2:1-4, 19-24