Matsya Purana — Cosmography of Jambūdvīpa: Varṣas
दशवर्षसहस्राणि आयुस्तेषामनामयम् कालाम्रस्य रसं पीत्वा ते सर्वे स्थिरयौवनाः //
daśavarṣasahasrāṇi āyusteṣāmanāmayam kālāmrasya rasaṃ pītvā te sarve sthirayauvanāḥ //
Their lifespan was ten thousand years, free from disease. Having drunk the juice of the kālāmra (dark mango), they all remained in steady, unfading youth.
It does not describe Pralaya directly; it depicts a perfected human condition in an early cosmic setting—disease-free longevity and stable youth—often contrasted with later-age decline that culminates in periodic dissolutions.
Indirectly, it frames an ethical ideal: when life is ordered and supported by dharma, existence is described as harmonious (health, stability). For kings and householders in the Matsya Purana, sustaining social order and right conduct is the practical counterpart to such “ideal conditions.”
No Vastu or temple-building rule is stated. The only ritual-adjacent point is symbolic: a sanctified “rasa/essence” is portrayed as sustaining vitality, a common Purāṇic motif for divine nourishment rather than a construction prescription.