Vṛddha-kanyā-carita and Balarāma’s Kurukṣetra Inquiry (वृद्धकन्या-चरितम् / कुरुक्षेत्रफल-प्रश्नः)
कुक्षौ चाप्यदधाद् हृष्टा तद् रेत: पुरुषर्षभ । सा दधार च त॑ गर्भ पुत्रहेतोर्महानदी,पुरुषप्रवर! उस महानदीने हर्षमें भरकर पुत्रके लिये उस वीर्यको अपनी कुक्षिमें रख लिया और इस प्रकार वह गर्भवती हो गयी
kukṣau cāpyadadhād hṛṣṭā tad retaḥ puruṣarṣabha | sā dadhāra ca taṃ garbhaṃ putrahetor mahānadī ||
Vaiśaṃpāyana said: Rejoicing, that great river received that seed into her womb, O best of men. Bearing it as an embryo for the sake of obtaining a son, she thus became pregnant.
वैशम्पायन उवाच
The verse highlights purposeful agency in the pursuit of lineage: the ‘great river’ consciously receives and bears the seed ‘for the sake of a son,’ reflecting the epic motif that progeny and succession are treated as weighty aims that can drive extraordinary, even non-ordinary, modes of conception.
Vaiśaṃpāyana narrates that a personified great river, delighted, takes the seed into her womb and carries it as an embryo with the intention of producing a son, thereby becoming pregnant.