Matsya Purana — Rite and Layout for Consecrating Ponds
तथा षोडशहस्तः स्यान् मण्डपश्च चतुर्मुखः वेद्याश्च परितो गर्ता रत्निमात्रास्त्रिमेखलाः //
tathā ṣoḍaśahastaḥ syān maṇḍapaśca caturmukhaḥ vedyāśca parito gartā ratnimātrāstrimekhalāḥ //
Likewise, the maṇḍapa should be sixteen hastas (cubits) in measure and four-faced (with four entrances). Around the altar-platform (vedī) there should be a trench (garta) and three encircling bands (tri-mekhalā), each of the measure of one ratni (span).
This verse does not discuss Pralaya; it belongs to the Matsya Purana’s Vastuvidya material, prescribing precise architectural/ritual measurements for a mandapa and vedī layout.
It supports the dharmic duty of patrons (kings/householders) to build and sponsor correctly proportioned ritual and temple structures; accurate measurements are treated as essential for auspiciousness and proper worship.
It specifies a standard mandapa size (16 hastas), a four-entranced plan (caturmukha), and a vedi arrangement with an encircling trench and three concentric bands/steps, each one ratni in measure—key Matsya Purana temple and ritual-platform design rules.