Matsya Purana — Solar Dynasty Prelude: Vivasvān–Saṃjñā–Chāyā
यस्माद् अविज्ञाततया मत्सकाशम् इहागता तस्मान्मदीयं भवनं प्रवेष्टुं न त्वमर्हसि //
yasmād avijñātatayā matsakāśam ihāgatā tasmānmadīyaṃ bhavanaṃ praveṣṭuṃ na tvamarhasi //
Since you have come here into my presence in ignorance—without recognition or proper understanding—therefore you are not fit to enter my dwelling.
It does not describe the mechanics of Pralaya directly; it stresses preparedness and proper understanding when approaching the divine guide who will later direct survival through the deluge narrative.
It implies a dharmic rule of approach: a ruler or householder should act with discernment, humility, and proper recognition before entering sacred or authoritative spaces—symbolizing disciplined conduct and respect for higher order.
While not a Vastu rule, it mirrors a ritual threshold principle: entry into a ‘bhavana’ (abode/sanctum) requires eligibility—purity, right intent, and correct recognition—akin to temple-entry decorum in later ritual manuals.