Mahabharata Anushasna Parva Chapter 162:5

Mahabharata Anushasna Parva (Dana Dharma Parva) Chapter 162:5 The flesh of the back-bone, or that of animals not slain in sacrifice, should be avoided even as one avoids the flesh of one's own son. One should never cause one's guest to go without food whether when one resides in one's own country or in a foreign land. After completing one's study one should present the Dakshina unto one's preceptor. When one sees one's preceptor, one should congratulate him with reverence and worshipping him present him a seat. By worshipping one's preceptor, one increases the period of one's life as also one's fame and prosperity. One should never censure the old, nor send them on any business[]. One should never be seated when any one that is old is standing. By acting in this way one protects the duration of one's life. One should never cast one's eyes on a naked woman, nor a naked man. One should never indulge in sexual congress except in privacy. One should eat also without being seen by others. Preceptors are the foremost of Tirthas; the heart is the foremost of all sacred objects; knowledge is the foremost of all objects of search; and contentment is the foremost of all happiness. Morning and evening one should listen to the grave counsels of those that are aged. One attains to wisdom by constant waiting upon those that are venerable for years. While reading the Vedas or employed in eating, one should use one's right hand. One should always keep one's speech and mind under thorough control, as also one's senses. With well-cooked frumenty, Yavaka, Krisara, and Havi (clarified butter), one should worship the Pitris and the deities in the Sraddha called Ashtaka. The same should be used in worshipping the Planets. One should not undergo a shave without calling down a blessing upon oneself. If one sneezes, one should be blessed by those present. All that are ill or afflicted with disease, should be blessed. The extension of their lives should be prayed for.[] One should never address an eminent person familiarly (by using the word Twam). Under even the great difficulties one should never do this.