Matsya Purana — Yuga Durations
नैवातिसात्त्विकः कश्चिन् न साधुर्न च सत्यवाक् नास्तिका ब्रह्मभक्ता वा जायन्ते तत्र मानवाः //
naivātisāttvikaḥ kaścin na sādhurna ca satyavāk nāstikā brahmabhaktā vā jāyante tatra mānavāḥ //
There, no one is truly sāttvika; none is virtuous or even truthful in speech. In that place (or time), people are born either as unbelievers (nāstikas) or as devotees of Brahman (the Supreme).
This verse does not describe Pralaya directly; it describes ethical and spiritual decline in human society, emphasizing the rarity of sāttvika virtue and truthfulness.
It functions as a warning: rulers and householders must actively uphold satya (truth), sādhu conduct, and sāttvika discipline, because society tends toward moral erosion; governance and personal vows should counteract this decline.
No Vāstu/temple-rule detail is stated in this verse; its practical takeaway is ritual-ethical—cultivating purity (sattva), truthfulness, and devotion as the foundation for any dharmic practice.