Adhyāya 166: Kṛtaghna-doṣa (कृतघ्नदोषः) — the fault of ingratitude and the limits of expiation
अभार्या शयने बिश्रच्छूद्रं वृद्धं च वै द्विज: । अब्राह्माणं मन््यमानस्तृणेष्वासीत पृष्ठत: । तथा संशुध्यते राजन् शृणु चात्र वचो मम
bhīṣma uvāca | abhāryā śayane viśracchūdraṁ vṛddhaṁ ca vai dvijaḥ | abrāhmaṇaṁ manyamānas tṛṇeṣv āsīta pṛṣṭhataḥ | tathā saṁśudhyate rājan śṛṇu cātra vaco mama ||
Bhishma said: “If a twice-born man places upon his bed a woman other than his lawful wife, or if he honors an aged Śūdra—or, regarding a non-Brahmin (such as a Kṣatriya or Vaiśya) as worthy of special respect, seats him on a higher seat while himself sits behind on a mat of grass—then he falls from the status and conduct of Brahminhood. O king, listen to me as I explain how such a man is purified.”
भीष्म उवाच
The verse warns that a Brahmin’s identity is sustained by disciplined conduct: sexual exclusivity with one’s lawful wife and careful observance of prescribed norms of honor and seating. Violations are framed as a ‘fall’ from Brahminhood, for which purification/atonement is then to be prescribed.
In the Shanti Parva’s dharma-instruction, Bhishma addresses the king and lists behaviors that cause a Brahmin to lose standing; he then signals that he will explain the method of purification (saṁśuddhi/prāyaścitta) for such lapses in the subsequent discussion.