Matsya Purana — Mandāra-Saptamī Vrata
माघस्यामलपक्षे तु पञ्चम्यां लघुभुङ्नरः दन्तकाष्ठं ततः कृत्वा षष्ठीमुपवसेद्बुधः //
māghasyāmalapakṣe tu pañcamyāṃ laghubhuṅnaraḥ dantakāṣṭhaṃ tataḥ kṛtvā ṣaṣṭhīmupavasedbudhaḥ //
In the pure bright fortnight of Māgha, on the fifth lunar day a man should eat lightly; then, having performed the rite of cleansing the teeth with a tooth-stick, the wise should observe a fast on the sixth day.
This verse does not address pralaya; it focuses on tithi-based ritual discipline in Māgha, emphasizing purity, restraint in diet, and fasting.
It prescribes a regulated routine—light eating on Pañcamī and fasting on Ṣaṣṭhī—reflecting the householder’s (and ruler’s) duty to practice self-control, cleanliness (śauca), and observance of vrata as part of dharma.
Ritually, it highlights preparatory purity: dental cleansing with dantakāṣṭha and graduated restraint leading into upavāsa; no Vāstu or temple-architecture rule is stated in this verse.