Mencius. Book 4, Part 1, Chapter 18.
Book 4, Le Low. Part 1.
1. Kung-sun Ch'ow said, "Why is it that the superior man does not himself teach his son?"
2. Mencius replied, "The circumstancs of the case forbids its being done. The teacher must inculcate what is correct. When he inculcates what is correct, and his lessons are not practiced he follows them up with being angry. When he follows them up with being angry, then, contrary to what should abe, he is offended with his son. At the same time, the pupil says, 'My master inculcates on me what is correct, and he himself does not proceed in a correct path.' The result of this is, that father and so are offended with each other. When father and son come to be offended with each other, the case is evil.
3. "The ancients exchanged sons, and one taught the sone of another.
4. "Between father and son, there should be no reproving admonitions to what is good. Such reproofs lead ot alienation, and than alienation, there is nothing more inauspicious."
Text source: The Works of Mencius. Translated by James Legge.