Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
अनग्निपक्कम् अश्नाति तृतीयायां तु यो नरः गां दत्त्वा शिवमभ्येति पुनरावृत्तिदुर्लभम् इह चानन्दकृत्पुंसां श्रेयोव्रतमिदं स्मृतम् //
anagnipakkam aśnāti tṛtīyāyāṃ tu yo naraḥ gāṃ dattvā śivamabhyeti punarāvṛttidurlabham iha cānandakṛtpuṃsāṃ śreyovratamidaṃ smṛtam //
That man who, on the third lunar day, eats food not cooked on fire and then gifts a cow, attains Śiva’s auspicious state—one from which return (to rebirth) is hard to come by. In this world too it becomes a source of joy for people; this observance is remembered as the Śreyovrata, the vow that leads to the highest good.
This verse does not discuss Pralaya; it focuses on dharma in the form of a vrata—dietary restraint on Tṛtīyā and the merit of cow-gifting leading toward liberation.
It prescribes a householder-style discipline: observing a tithi-based restraint (avoiding fire-cooked food) and performing go-dāna. For rulers too, it reinforces public dharma—charity, self-control, and supporting sacred economy through gifting.
Ritually, it specifies a tithi-observance (Tṛtīyā) and a concrete dāna (cow-gift) as the core act; no Vāstu or temple-construction rule is mentioned in this particular śloka.