Matsya Purana — The Cave-Sanctuary: Jewel-Lake
जानुनाकुञ्चितस्त्वेको देवदेवस्य चक्रिणः फणीन्द्रसंनिविष्टो ऽङ्घ्रिर् द्वितीयश्च तथानघ //
jānunākuñcitastveko devadevasya cakriṇaḥ phaṇīndrasaṃniviṣṭo 'ṅghrir dvitīyaśca tathānagha //
O sinless one, of the Lord of gods who bears the discus, one leg should be bent at the knee, and the second foot should be placed upon the serpent‑king (Śeṣa).
It does not directly discuss pralaya; instead, it preserves the postural canon for depicting Vishnu, supporting correct ritual visualization and temple worship that remain constant across cosmic cycles.
By prescribing correct forms for sacred images, it supports dharmic patronage—kings and householders gain merit by commissioning, installing, and worshipping properly made Vishnu mūrtis according to śāstric rules.
This is a pratima-lakṣaṇa instruction: Vishnu’s stance is defined—one leg bent at the knee and the other foot resting on Śeṣa—guiding sculptors, temple planners, and priests in accurate icon-making and installation.