Matsya Purana — Bhīma-Dvādaśī
*मत्स्य उवाच पुरा रथंतरे कल्पे परिपृष्टो महात्मना मन्दरस्थो महादेवः पिनाकी ब्रह्मणा स्वयम् //
*matsya uvāca purā rathaṃtare kalpe paripṛṣṭo mahātmanā mandarastho mahādevaḥ pinākī brahmaṇā svayam //
Matsya said: Formerly, in the Rathantara Kalpa, the great Lord—Mahādeva, bearer of the Pināka bow—abiding on Mount Mandara, was questioned in person by the great-souled Brahmā.
It does not describe Pralaya directly; it situates the teaching in a specific cosmic era (the Rathantara Kalpa), a typical Purāṇic way of anchoring doctrines within vast cycles of creation.
Indirectly: it establishes an authoritative transmission—Brahmā questioning Śiva—implying that subsequent instructions (often including dharma, ritual, or governance norms) are grounded in a revered teacher–questioner lineage.
No Vāstu or ritual procedure is specified in this verse; it functions as a preface indicating that a formal doctrinal exposition is about to begin, delivered in a sacred setting (Mandara) by a principal deity (Śiva).