Matsya Purana — Yayāti and His Sons: The Exchange of Youth and Old Age
प्रजाश्च यौवनं प्राप्ता विनश्यन्ति ह्य् अनो तव अग्निप्रस्कन्दनगतस् त्वं चाप्येवं भविष्यसि //
prajāśca yauvanaṃ prāptā vinaśyanti hy ano tava agnipraskandanagatas tvaṃ cāpyevaṃ bhaviṣyasi //
Even your subjects, having reached youth, pass away, O Anu; so too will you—once you enter the onward course of the fire (of time and decay), you will likewise come to that end.
It stresses the inevitability of decline under time’s consuming force—an ethical preface to Pralaya themes by reminding Manu that all embodied beings, even in youth, are carried toward dissolution.
By highlighting that both subjects and ruler are mortal, it urges governance and household life grounded in dharma, restraint, and non-attachment—acting rightly without pride in youth, power, or longevity.
No direct Vastu or ritual rule is stated; the takeaway is preparatory—rituals, gifts, and sacred works should be done promptly because time ‘burns onward’ and life is uncertain.