Matsya Purana — Navagraha Sacrifice for Planetary Pacification and Prosperity
द्विहस्तविस्तृतं तद्वच् चतुर्हस्तायतं पुनः लक्षहोमे भवेत्कुण्डं योनिवक्त्रं त्रिमेखलम् //
dvihastavistṛtaṃ tadvac caturhastāyataṃ punaḥ lakṣahome bhavetkuṇḍaṃ yonivaktraṃ trimekhalam //
For a lakṣa-homa, the fire-pit (kuṇḍa) should be two hastas in breadth and four hastas in length; it should be fashioned with a yoni-shaped mouth (yoni-vaktra) and provided with three encircling bands (tri-mekhalā).
This verse does not discuss pralaya; it gives technical rules for constructing a ritual fire-pit used in a large-scale homa (lakṣa-home).
It supports the dharmic duty of performing properly regulated sacrifices: a king or householder undertaking a major homa must follow prescribed measurements and forms to ensure the rite is valid and efficacious.
It specifies the kuṇḍa’s exact size (2 hastas wide, 4 hastas long) for a 100,000-oblation homa and mandates a yoni-shaped opening and three mekhālās—features central to correct ritual-architecture (yajña-vāstu).