Matsya Purana — The Glory of Prayaga: Pilgrimage
दुष्प्राप्यं मानुषैः पुण्यं प्रयागं तु युधिष्ठिर देवदानवगन्धर्वा ऋषयः सिद्धचारणाः तदुपस्पृश्य राजेन्द्र स्वर्गलोकमुपासते //
duṣprāpyaṃ mānuṣaiḥ puṇyaṃ prayāgaṃ tu yudhiṣṭhira devadānavagandharvā ṛṣayaḥ siddhacāraṇāḥ tadupaspṛśya rājendra svargalokamupāsate //
O Yudhiṣṭhira, sacred Prayāga is difficult for human beings to attain. Gods, Dānavas, Gandharvas, Ṛṣis, Siddhas, and Cāraṇas—having bathed there, O king—abide in the heavenly world.
This verse does not discuss Pralaya; it teaches tirtha-mahātmyā—how the sacred place Prayāga is exceptionally meritorious and leads to heavenly attainment.
It frames pilgrimage and ritual bathing (snāna) as a dharmic practice even for rulers—encouraging kings and householders to seek merit through tīrtha-yātrā and purification rites.
The ritual point is tīrtha-snāna (upaspṛśya—ablution/bathing) at Prayāga; no temple-architecture (vāstu) rule is stated in this verse.