Matsya Purana — The Tale of Brahmadatta: Past-life Memory
आस्थाय नियमं तस्थौ सप्तरात्रमकल्मषः स्वप्ने प्राह हृषीकेशः प्रभाते पर्यटन्पुरम् //
āsthāya niyamaṃ tasthau saptarātramakalmaṣaḥ svapne prāha hṛṣīkeśaḥ prabhāte paryaṭanpuram //
Having undertaken a niyama (disciplined observance), the sinless one remained steadfast for seven nights. In a dream Hṛṣīkeśa (Lord Viṣṇu) spoke to him; and at dawn he went about the city.
This verse does not describe pralaya directly; it highlights a dharmic method—strict niyama and purity—through which divine guidance (Viṣṇu’s message in a dream) is received.
It presents the ideal of regulated self-discipline (niyama), moral purity (akalmaṣa), and purposeful daily conduct—suggesting that rulers/householders should combine vows and inner restraint with active engagement in civic life (“going about the city”).
Ritually, it emphasizes vrata/niyama kept for a defined period (seven nights) and the reception of divine instruction; architecturally, it only alludes indirectly to moving through the city (puram) and does not state specific Vāstu or temple-building rules in this line.