Matsya Purana — Tripura Takes Refuge in the Ocean; Maya’s Hidden Nectar-Reservoir and the God...
यूयं यत्प्रथमं दैत्याः पश्चाच्च बलपीडिताः प्रविष्टा नगरं त्रासात् प्रमथैर्भृशमर्दिताः //
yūyaṃ yatprathamaṃ daityāḥ paścācca balapīḍitāḥ praviṣṭā nagaraṃ trāsāt pramathairbhṛśamarditāḥ //
You Daityas—who at first came forward—later, when your strength was crushed, entered the city out of fear, being fiercely harried by the Pramathas.
This verse does not address Pralaya; it depicts a battlefield reversal where the Daityas, overwhelmed, flee into a city while being pursued by the Pramathas.
Indirectly, it reflects a political-ethical theme common in the Matsya Purana: when force collapses and panic spreads, city-entry becomes a defensive refuge—implying the importance of protection, preparedness, and disciplined retreat in governance and public safety.
No explicit Vastu or ritual rule is stated; the only relevant takeaway is the city (nagara) as a fortified refuge in Purāṇic warfare imagery, often tied elsewhere in the Matsya Purana to urban planning and defenses.