Matsya Purana — Glory of Prayaga: The Fruit of the Anashaka Fast and the Merit of the Yamuna
*मार्कण्डेय उवाच तपनस्य सुता देवी त्रिषु लोकेषु विश्रुता समाख्याता महाभागा यमुना तत्र निम्नगा //
*mārkaṇḍeya uvāca tapanasya sutā devī triṣu lokeṣu viśrutā samākhyātā mahābhāgā yamunā tatra nimnagā //
Mārkaṇḍeya said: The goddess Yamunā—daughter of Tapana (the Sun)—is renowned throughout the three worlds; she is celebrated as supremely fortunate, and there she flows as the descending river-current.
This verse does not discuss Pralaya; it identifies Yamunā as a divine river-goddess of solar lineage (daughter of Tapana/Sūrya) and emphasizes her cosmic renown across the three worlds.
Indirectly, it supports the Purāṇic ethic of honoring tīrthas: kings and householders are encouraged to protect sacred rivers and undertake pilgrimage, charity, and purification rites associated with renowned river-deities like Yamunā.
No Vāstu or temple-measurement rule is stated here; the ritual takeaway is that Yamunā is explicitly named a devī and therefore a proper focus for river-worship (snāna, tarpaṇa, and tīrtha observances) within tīrtha-māhātmya sections.