Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
यश्चोभयमुखीं दद्यात् प्रभूतकनकान्विताम् दिनं पयोव्रतस्तिष्ठेत् स याति परमं पदम् एतद्धेनुव्रतं नाम पुनरावृत्तिदुर्लभम् //
yaścobhayamukhīṃ dadyāt prabhūtakanakānvitām dinaṃ payovratastiṣṭhet sa yāti paramaṃ padam etaddhenuvrataṃ nāma punarāvṛttidurlabham //
Whoever donates a cow fashioned with two mouths and adorned with abundant gold, and who for one day observes the milk-vow (payo-vrata), attains the supreme state. This observance is called the Henu-vrata, and it is said to grant a goal from which return to repeated rebirth is hard to come by.
This verse does not address Pralaya; it teaches a dharma-practice (a vow and gift) whose fruit is liberation-like attainment (paramaṁ padam) beyond recurring rebirth.
It frames ideal householder/royal conduct as dana (charitable gifting) combined with vrata (self-restraint): donating a ritually significant cow-gift and observing a one-day milk-vow as a disciplined act of merit leading toward the highest spiritual goal.
The significance is ritual rather than architectural: it prescribes the Henu-vrata—donation of a specially described cow (ubhaya-mukhī) adorned with gold, alongside a payo-vrata (milk-observance) for one day.