Matsya Purana — Ravi-Saṅkrānti Vow: Udyāpana
अयने विषुवे वापि संक्रान्तिव्रतमाचरेत् पूर्वेद्युरेकभक्तेन दन्तधावनपूर्वकम् संक्रान्तिवासरे प्रातस् तिलैः स्नानं विधीयते //
ayane viṣuve vāpi saṃkrāntivratamācaret pūrvedyurekabhaktena dantadhāvanapūrvakam saṃkrāntivāsare prātas tilaiḥ snānaṃ vidhīyate //
On an ayana (solstitial turning) or on a viṣuva (equinox) as well, one should undertake the Saṃkrānti vow. On the previous day, having first cleansed the teeth, one should eat only once; and on the day of Saṃkrānti itself, an early-morning bath with sesame (tila) is prescribed.
This verse does not discuss pralaya directly; it focuses on dharmic timekeeping—treating solar turning-points (ayana/viṣuva/saṃkrānti) as ritually potent moments requiring purification and restraint.
It sets a practical vrata for disciplined living: the householder (and by extension a king as exemplar) should observe restraint (single meal the prior day) and bodily purity (tooth-cleaning and dawn bath), aligning personal conduct with sacred calendrical transitions.
The ritual takeaway is the Saṃkrānti procedure: prepare with ekabhakta on the previous day and perform an early-morning tila-snāna on Saṃkrānti—an auspicious purification commonly paired with dāna and other rites in Purāṇic practice.