Matsya Purana — Catalogue of the Eighteen Puranas
यत्र धर्मार्थकामानां मोक्षस्य च रसातले माहात्म्यं कथयामास कूर्मरूपी जनार्दनः //
yatra dharmārthakāmānāṃ mokṣasya ca rasātale māhātmyaṃ kathayāmāsa kūrmarūpī janārdanaḥ //
There, in Rasātala (the nether region), Janārdana in the form of the Tortoise expounded the sacred greatness connected with dharma, artha, kāma, and also mokṣa.
This verse is not directly about pralaya; it highlights Viṣṇu (as Kūrma) teaching a māhātmya in Rasātala that frames spiritual goals (including mokṣa) rather than cosmic dissolution.
By naming dharma, artha, and kāma together with mokṣa, the verse implies an integrated life-model: rulers and householders should pursue prosperity and legitimate desires under dharma, while keeping liberation as the highest horizon.
No specific Vāstu or temple-building rule is stated; the ritual takeaway is the genre-marker “māhātmya,” indicating sanctifying praise/teaching connected to sacred realms that can orient practice toward the puruṣārthas, especially mokṣa.