Proverbs 9:9

Pro 9:9 Give [instruction] to a wise [man], and he will be yet wiser: teach a just [man], and he will increase in learning.

Ver. 9. Give admonition to a wise man. ] This is an alms that the poorest may give, and be never the poorer, but the better. For by instructing another, a man engageth himself, lest he hear, "Physician heal thyself." Turpe est doctori, cum culpa redarguit ipsum. See my "Common Place of Admonition."