Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
मासोपवासी यो दद्याद् धेनुं विप्राय शोभनाम् स वैष्णवं पदं यति भीमव्रतमिदं स्मृतम् //
māsopavāsī yo dadyād dhenuṃ viprāya śobhanām sa vaiṣṇavaṃ padaṃ yati bhīmavratamidaṃ smṛtam //
Whoever observes a month-long fast and gives a fine cow to a brāhmaṇa attains the Vaiṣṇava state, the supreme abode of Viṣṇu. This is remembered as the Bhīma-vrata (the Great Vow).
This verse does not address pralaya; it focuses on dharma—specifically a vow (vrata) and gift (dāna) that lead to attaining the Vaiṣṇava abode.
It presents a householder-accessible discipline: sustained fasting (self-restraint) paired with charitable giving (cow-gift to a qualified brāhmaṇa), framed as a meritorious path culminating in a Vaiṣṇava spiritual goal.
The ritual significance is the Bhīmavrata: month-long upavāsa and dhenu-dāna. No Vāstu or temple-architecture rule is stated in this specific verse.