Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
विप्राय दद्याच्छङ्खं च स पदं याति शांकरम् राजा भवति कल्पान्ते धृतिव्रतमिदं स्मृतम् //
viprāya dadyācchaṅkhaṃ ca sa padaṃ yāti śāṃkaram rājā bhavati kalpānte dhṛtivratamidaṃ smṛtam //
If one gives a conch (śaṅkha) to a brāhmaṇa, one attains the station of Śaṅkara; and at the end of the aeon (kalpa) one becomes a king—this is remembered as the Dhṛti-vrata, the vow of steadfastness.
It does not describe pralaya directly; it uses the long cosmic time-marker “kalpānta” (end of an aeon) to state the delayed fruition of merit from dāna—culminating in kingship in a future cycle.
It frames dāna as a concrete dharmic duty: gifting a ritually significant object (a conch) to a brāhmaṇa is presented as a vrata with both spiritual reward (Śiva’s station) and worldly reward (future kingship), aligning household and royal ethics with generosity and patronage.
The ritual significance is the śaṅkha, a sacred implement used in pūjā and temple rites (auspicious proclamation and consecratory sound); donating such a liturgical object is treated as a high-merit act within Purāṇic ritual culture.