Matsya Purana — Catalogue of the Eighteen Puranas
पुराणमेकमेवासीत् तदा कल्पान्तरे ऽनघ त्रिवर्गसाधनं पुण्यं शतकोटिप्रविस्तरम् //
purāṇamekamevāsīt tadā kalpāntare 'nagha trivargasādhanaṃ puṇyaṃ śatakoṭipravistaram //
O sinless one, at the close of a former aeon there existed only a single Purāṇa—holy in nature, a means to accomplish the three aims of life (dharma, artha, and kāma), and vast in extent, spreading over a hundred koṭi (of verses).
It points to kalpa-cycle transitions (kalpānta), implying that at an earlier cosmic turning-point the Purāṇic knowledge was preserved as a single, primordial corpus.
By calling the Purāṇa a means to achieve the trivarga (dharma, artha, kāma), it frames Purāṇic instruction as practical guidance for righteous living, prosperity, and regulated enjoyment—central concerns for both rulers and householders.
No direct vāstu/temple rule appears in this verse; its ritual takeaway is broader—Purāṇic teaching is presented as inherently meritorious (puṇya) and authoritative, forming a foundation upon which later ritual and iconographic instructions stand.