Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
माघे निश्यार्द्रवासाः स्यात् सप्तम्यां गोप्रदो भवेत् दिवि कल्पमुषित्वेह राजा स्यात्पवनं व्रतम् //
māghe niśyārdravāsāḥ syāt saptamyāṃ goprado bhavet divi kalpamuṣitveha rājā syātpavanaṃ vratam //
In the month of Māgha, one should wear garments moistened by the night (dew). On the seventh lunar day, one should give a cow in charity. Having dwelt in heaven for an aeon (kalpa), one becomes a king here on earth. This is called the Pavana vow (Wind/Purifying vow).
This verse is not about pralaya; it belongs to vrata-phalāni (results of vows), describing a Māgha observance and its karmic fruit (heavenly enjoyment and later kingship).
It prescribes householder-style dharma: bodily discipline (austerity through dew-damp clothing) and charity (go-dāna on Saptamī), teaching that purity and generosity are foundations for prosperity and rulership.
The significance is ritual rather than architectural: it defines a specific tithi-based observance in Māgha, culminating in cow-gift charity, and names the practice as the Pavana (purifying) vrata.