Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
नक्ताशी चाष्टमीषु स्याद् वत्सरान्ते च धेनुदः पौरंदरं पुरं याति सुगतिव्रतमुच्यते //
naktāśī cāṣṭamīṣu syād vatsarānte ca dhenudaḥ pauraṃdaraṃ puraṃ yāti sugativratamucyate //
On the Aṣṭamī days (the eighth lunar days), let him eat only at night; and at the end of the year, having gifted a cow, he attains the city of Purandara (Indra). This is called the Sugati-vrata, the vow that leads to a good destiny.
This verse does not address pralaya; it focuses on vrata-dharma—specific fasting discipline and cow-gift (dāna) as means to attain heavenly merit.
It presents a householder-style observance: regulated eating on aṣṭamī and a prescribed charitable gift at year’s end. Such vows exemplify self-restraint (niyama) and generosity (dāna), key duties praised in the Matsya Purana’s ethical teaching.
The ritual significance is the aṣṭamī-based naktāśī observance and the concluding cow-donation; no Vastu or temple-architecture rule is mentioned in this verse.