Matsya Purana — Kailasa
तत्र संवर्तको नाम सो ऽग्निः पिबति तज्जलम् अग्निः समुद्रवासस्तु और्वो ऽसौ वडवामुखः //
tatra saṃvartako nāma so 'gniḥ pibati tajjalam agniḥ samudravāsastu aurvo 'sau vaḍavāmukhaḥ //
There, the fire called Saṃvartaka drinks up that water. That ocean-dwelling fire is the Aurva, known as the Mare’s Mouth (Vaḍavāmukha).
It identifies the pralaya mechanism where the Saṃvartaka fire absorbs/drinks the waters, specifically linked with the submarine Aurva fire (Vaḍavāmukha) said to dwell in the ocean.
Indirectly, it supports Matsya Purana’s ethic of impermanence: rulers and householders should govern and live with restraint and dharma, knowing even oceans and worlds are subject to dissolution by cosmic law.
No direct Vastu or ritual procedure is stated; the takeaway is cosmological—recognizing sacred geography and elemental forces (fire and water) that later inform ritual cosmology and temple symbolism.