Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
विप्रायेन्धनदो यस्तु वर्षादिचतुरस्त्वृतून् घृतधेनुप्रदो ऽन्ते च स परं ब्रह्म गच्छति वैश्वानरव्रतं नाम सर्वपापविनाशनम् //
viprāyendhanado yastu varṣādicaturastvṛtūn ghṛtadhenuprado 'nte ca sa paraṃ brahma gacchati vaiśvānaravrataṃ nāma sarvapāpavināśanam //
Whoever, through the four seasons beginning with the rains, gives firewood to a Brāhmaṇa, and at the conclusion of the vow donates a ghee-yielding cow (ghṛta), attains the Supreme Brahman. This is called the Vaiśvānara-vrata, the vow that destroys all sins.
It does not discuss pralaya directly; it teaches a purificatory vow (Vaiśvānara-vrata) whose merit is said to erase sins and lead to the Supreme Brahman.
It frames dharma through disciplined seasonal giving: supporting sacred fires and Vedic livelihoods by donating fuel to a Brāhmaṇa over the yearly cycle, then completing the observance with a major gift (a ghee-yielding cow).
The ritual focus is Vaiśvānara (sacred fire): the vow centers on sustaining fire-rites through fuel-giving and concluding with a prescribed dāna, rather than on vāstu or temple construction.