Matsya Purana — Catalogue of the Eighteen Puranas
विषुवे हेममत्स्येन धेन्वा चैव समन्वितम् यो दद्यात्पृथिवी तेन दत्ता भवति चाखिला //
viṣuve hemamatsyena dhenvā caiva samanvitam yo dadyātpṛthivī tena dattā bhavati cākhilā //
Whoever, on the day of Viṣuva, gives in charity a symbolic ‘earth’ gift accompanied by a golden fish and a cow—by him the entire earth is deemed to have been given.
It does not describe Pralaya directly; it uses the symbol of ‘the earth’ (pṛthivī) in charity, teaching that a properly constituted Viṣuva gift yields merit equivalent to donating the whole world.
It frames dāna as a core dharma: a householder (and especially a king who possesses resources) should perform time-specific, ritually complete gifts—here, the Viṣuva donation—so that limited offerings gain expansive religious merit.
Ritually, it concerns Viṣuva-kāla dāna and symbolic ‘bhū-dāna’ (earth-gift) augmented by a golden fish and a cow—indicating prescribed components that make the offering ‘complete’ and thus maximally meritorious.