Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
प्रतिपद्येकभक्ताशी समान्ते कपिलाप्रदः वैश्वानरपदं याति शिवव्रतमिदं स्मृतम् //
pratipadyekabhaktāśī samānte kapilāpradaḥ vaiśvānarapadaṃ yāti śivavratamidaṃ smṛtam //
He who, beginning on the pratipad (first lunar day), eats only once a day, and at the conclusion gives a tawny cow (kapilā) as a gift, attains the state of Vaiśvānara. This is remembered as the Śiva‑vrata (vow sacred to Śiva).
It does not discuss pralaya; it focuses on dharma—how a regulated vow and concluding gift lead to a higher spiritual state (Vaiśvānara-pada).
It prescribes a practical householder-style observance: disciplined eating (ekabhakta) and dāna (gift of a kapilā cow) as meritorious conduct that supports personal purification and social-religious responsibility.
The significance is ritual rather than architectural: the vrata begins on pratipad, follows a dietary rule (one meal daily), and is completed with a formal donation (kapilā-dāna), which is stated to yield Vaiśvānara-pada.