Matsya Purana — Catalogue of the Eighteen Puranas
रथंतरस्य कल्पस्य वृत्तान्तमधिकृत्य च सावर्णिना नारदाय कृष्णमाहात्म्यमुत्तमम् //
rathaṃtarasya kalpasya vṛttāntamadhikṛtya ca sāvarṇinā nāradāya kṛṣṇamāhātmyamuttamam //
And, taking up the account of the Rathaṃtara Kalpa, Sāvarṇi narrated to Nārada the unsurpassed greatness (māhātmya) of Śrī Kṛṣṇa.
It situates the teaching within a specific Kalpa (Rathaṃtara), implying a cosmological framework of recurring aeons where creation and dissolution are discussed as part of Kalpa-accounts, though this verse itself primarily introduces the narrative focus.
Indirectly: by elevating Krishna’s māhātmya within a Kalpa narrative, it frames dharma as grounded in devotion and cosmic order; such Purāṇic glorifications commonly function as ethical-theological orientation for rulers and householders, even if no direct duty is stated here.
No explicit Vāstu or temple-rule is stated; the ritual takeaway is that hearing/reciting Krishna’s māhātmya is treated as a meritorious Purāṇic act, often linked to śravaṇa (listening) and kīrtana (praise) practices.