न तु जात्या समा लोके ब्राह्याण्या: क्षत्रिया भवेत् ब्राह्माण्या: प्रथम: पुत्रो भूयान् स्थाद् राजसत्तम
na tu jātyā samā loke brāhmaṇyāḥ kṣatriyā bhavet | brāhmaṇyāḥ prathamaḥ putro bhūyān sthād rājasattama ||
Bhīṣma said: “In this world, a Kṣatriya woman is not equal in birth-status to a Brāhmaṇa woman. The first-born son of a Brāhmaṇa woman should be regarded as the more eminent—O best among kings.”
भीष्म उवाच
Bhīṣma asserts a hierarchy based on jāti/varṇa: a Brāhmaṇa woman is presented as higher in birth-status than a Kṣatriya woman, and the eldest son of a Brāhmaṇa woman is to be treated as especially eminent. The ethical thrust is about social precedence and inherited status within the dharma framework being discussed.
In Anuśāsana Parva, Bhīṣma is instructing the king on dharma and social norms. Here he addresses the king directly (“O best of kings”) while laying down a rule of precedence concerning women of different varṇas and the status accorded to a Brāhmaṇa woman’s first-born son.