Shloka 27
Adhyāya 166: Kṛtaghna-doṣa (कृतघ्नदोषः) — the fault of ingratitude and the limits of expiation
उदपानोदके ग्रामे ब्राह्मणो वृषलीपति: । उषित्वा द्वादश समा: शूद्रकर्मेव गच्छति,जिस गाँवमें एक ही कुएँका पानी सब लोग पीते हैं, वहाँ बारह वर्षोतक निवास करनेसे तथा शूद्रजातिकी स्त्रीके साथ विवाह कर लेनेसे ब्राह्मण भी शूद्र हो जाता है
udapānodake grāme brāhmaṇo vṛṣalīpatiḥ | uṣitvā dvādaśa samāḥ śūdrakarmāiva gacchati ||
भीष्म उवाच—ग्रामे यत्रोदपानोदकं सर्वैः पीयते, तत्र ब्राह्मणो वृषलीपतिः द्वादश समा उषित्वा शूद्रकर्मेव गच्छति।
भीष्म उवाच
Educational Q&A
The verse teaches that varṇa-identity and eligibility for particular dharmas are not treated as merely nominal; sustained association, marriage alliance, and long-term residence within a community—together with adopting its customary occupations—can lead society to regard a person as having shifted into that community’s mode of life and duties.
In the Śānti Parva’s dharma-instruction, Bhishma is laying down a rule-like observation about social status: a Brahmin who marries a Śūdra woman and lives for twelve years in a village characterized by common use of a single well is said to ‘go to’ (i.e., be classed as) one following Śūdra conduct/occupation.