Matsya Purana — The Greatness and Procedure of the Sarva-Phala-Tyaga Vrata
मार्गशीर्षे शुभे मासि तृतीयायां मुने व्रतम् द्वादश्यामथवाष्टम्यां चतुर्दश्यामथापि वा आरभेच्छुक्लपक्षस्य कृत्वा ब्राह्मणवाचनम् //
mārgaśīrṣe śubhe māsi tṛtīyāyāṃ mune vratam dvādaśyāmathavāṣṭamyāṃ caturdaśyāmathāpi vā ārabhecchuklapakṣasya kṛtvā brāhmaṇavācanam //
O sage, in the auspicious month of Mārgaśīrṣa one should commence the vow on the third lunar day; or else on the twelfth, the eighth, or even the fourteenth, during the bright fortnight (śukla-pakṣa), after arranging for a Brāhmaṇa to perform the recitation.
Nothing directly—this verse is procedural, prescribing auspicious dates and a preliminary sacred recitation for beginning a vrata, not describing pralaya or cosmogony.
It frames dharmic discipline as time-bound and scripture-guided: a householder (and likewise a king setting public religious standards) should begin vows on approved tithis in the bright fortnight and sanctify the act through a Brāhmaṇa’s recitation.
Ritual significance: it specifies tithi selection in Mārgaśīrṣa and requires brāhmaṇa-vācana (authoritative sacred reading/recitation) as a formal preface to initiating the vow.