Matsya Purana — The Maheshvara Vow: Śiva-Caturdaśī Vrata
पञ्चगव्यं ततो बिल्वं कर्पूरं चागुरुं यवाः तिलाः कृष्णाश्च विधिवत् प्राशनं क्रमशः स्मृतम् प्रतिमासं चतुर्दश्योर् एकैकं प्राशनं स्मृतम् //
pañcagavyaṃ tato bilvaṃ karpūraṃ cāguruṃ yavāḥ tilāḥ kṛṣṇāśca vidhivat prāśanaṃ kramaśaḥ smṛtam pratimāsaṃ caturdaśyor ekaikaṃ prāśanaṃ smṛtam //
First, pañcagavya is to be taken; thereafter bilva, camphor, and aguru; then barley, sesame, and black gram—this is remembered as the proper sequence for ritual ingestion. Each month, on the two caturdaśī days (the fourteenth lunar days), one of these is to be taken, one item at a time.
This verse is not about Pralaya; it prescribes a monthly ritual discipline (vrata-style purification) using specific substances to be taken in a regulated sequence.
It reflects the householder/kingly duty to maintain personal purity and religious discipline through calendrical observances—here, a regulated prāśana on the caturdaśī tithis each month.
The significance is ritual rather than architectural: it outlines a prāśana-krama (sequence of ingesting purificatory/fragrant and grain substances) to be performed monthly on caturdaśī.