Matsya Purana — Catalogue of the Eighteen Puranas
यत्राह नारदो धर्मान् बृहत्कल्पाश्रयाणि च पञ्चविंशत्सहस्राणि नारदीयं तदुच्यते //
yatrāha nārado dharmān bṛhatkalpāśrayāṇi ca pañcaviṃśatsahasrāṇi nāradīyaṃ taducyate //
That work in which Nārada expounds the principles of dharma, together with matters grounded in the Great Kalpa, and which extends to twenty-five thousand verses, is called the Nāradīya Purāṇa.
It does not narrate Pralaya directly; it situates dharma-teachings within a Kalpa framework (“Bṛhat Kalpa”), implying a cosmic timescale context rather than a flood/dissolution episode.
By identifying a dharma-focused source attributed to Nārada, it points readers toward a tradition of practical ethical duties (rāja-dharma and gṛhastha-dharma) preserved and systematized in Purāṇic literature.
No explicit Vāstu or iconography rule appears here; the verse is bibliographic—defining the Nāradīya by its dharma content, Kalpa-basis, and length (25,000 verses).