Matsya Purana — The Viśokā-Saptamī Vow
माघे कृष्णतिलैः स्नात्वा षष्ठ्यां वै शुक्लपक्षतः कृताहारः कृसरया दन्तधावनपूर्वकम् उपवासव्रतं कृत्वा ब्रह्मचारी भवेन्निशि //
māghe kṛṣṇatilaiḥ snātvā ṣaṣṭhyāṃ vai śuklapakṣataḥ kṛtāhāraḥ kṛsarayā dantadhāvanapūrvakam upavāsavrataṃ kṛtvā brahmacārī bhavenniśi //
No mês de Māgha, após banhar-se com água misturada com gergelim preto (kṛṣṇa-tila), no sexto dia lunar da quinzena clara, deve primeiro limpar os dentes e então alimentar-se apenas de kṛsarā (prato simples de arroz e leguminosas). Em seguida, tendo assumido o voto de jejum (upavāsa-vrata), à noite deve observar brahmacarya (continência celibatária).
This verse is not about pralaya; it prescribes a Māgha-month religious observance (bathing, regulated food, fasting, and night-time brahmacarya) as a means of purification and merit.
It frames dharma as disciplined self-restraint: even householders (and rulers) are encouraged to adopt periodic fasting, purity practices, and sexual restraint on vrata days to cultivate self-control and religious merit.
The significance is ritual (not architectural): Māgha snāna with black sesame, eating only kṛsarā after tooth-cleaning, undertaking upavāsa, and observing brahmacarya at night are given as the procedural steps of the vow.