Matsya Purana — Catalogue of the Eighteen Puranas
पुराणं ब्रह्मवैवर्तं यो दद्यान्माघमासि च पौर्णमास्यां शुभदिने ब्रह्मलोके महीयते //
purāṇaṃ brahmavaivartaṃ yo dadyānmāghamāsi ca paurṇamāsyāṃ śubhadine brahmaloke mahīyate //
Whoever gifts the Brahma-vaivarta Purāṇa in the month of Māgha, on the auspicious day of the full moon, is honored and exalted in Brahmaloka, the world of Brahmā.
This verse does not describe pralaya; it teaches the merit (phala) of a specific religious gift—donating a Purāṇa—resulting in honor in Brahmaloka.
It frames śāstra-dāna (gifting sacred literature) as a dharmic act suitable for householders and patrons (including kings), especially when performed on calendrically auspicious occasions like Māgha Paurṇamāsī.
The ritual significance is timing: the verse highlights Māgha month and the full-moon day as especially auspicious for performing Purāṇa-dāna.