Mbh 2.63.2

“Vidura addressing Dhritarashtra, said, ‘O monarch, tell us (impartially) like a witness what thou thinkest of the conduct of those who abandon their serving-men thus for giving instruction to them. The hearts of kings are, indeed, very fickle. Granting protection at first, they strike with clubs at last. O prince (Duryodhana), thou regardest thyself as mature in intellect, and, O thou of bad heart, thou regardest me as a child. But consider that he is a child who having first accepted one for a friend, subsequently findeth fault with him. An evil-hearted man can never be brought to the path of rectitude, like an unchaste wife in the house of a well-born person. Assuredly, instruction is not agreeable to this bull of the Bharata race like a husband of sixty years to a damsel that is young. After this, O king, if thou wishest to hear words that are agreeable to thee, in respect of all acts good or bad, ask thou women and idiots and cripples or persons of that description. A sinful man speaking words that are agreeable may be had in this world. But a speaker of words that are disagreeable though sound as regimen, or a hearer of the same, is very rare. He indeed, is a king’s true ally who disregarding what is agreeable or disagreeable to his master beareth himself virtuously and uttereth what may be disagreeable but necessary as regimen. O great king, drink thou that which the honest drink and the dishonest shun, even humility, which is like a medicine that is bitter, pungent, burning, unintoxicating, disagreeable, and revolting. And drinking it, O king, regain thou thy sobriety. I always wish Dhritarashtra and his sons affluence and fame. Happen what may unto thee, here I bow to thee (and take my leave). Let the Brahmanas wish me well. O son of Kuru, this is the lesson I carefully inculcate, that the wise should never enrage such as adders as have venom in their very glances!”