Matsya Purana — Glory of Prayaga: The Fruit of the Anashaka Fast and the Merit of the Yamuna
तत्र स्नात्वा दिवं यान्ति ये मृतास्ते ऽपुनर्भवाः एवं तीर्थसहस्राणि यमुनादक्षिणे तटे //
tatra snātvā divaṃ yānti ye mṛtāste 'punarbhavāḥ evaṃ tīrthasahasrāṇi yamunādakṣiṇe taṭe //
Having bathed there, those who die there go to heaven; they become ‘not born again’. Thus are found thousands of sacred fords (tīrthas) along the southern bank of the Yamunā.
It does not discuss pralaya; it teaches tīrtha-māhātmya—how bathing at a sacred ford and dying there is said to lead to heaven and freedom from rebirth.
It supports the householder/kingly duty of dharmic pilgrimage and river-bathing (snāna) as a merit-making practice, encouraging public support for access to tīrthas and observance of sacred rites.
Ritually, it highlights snāna at a Yamunā tīrtha as a powerful rite; architecturally it implies the importance of maintaining ghāṭas (bathing steps) and tīrtha infrastructure along the riverbank.