Matsya Purana — Navagraha Sacrifice for Planetary Pacification and Prosperity
तथा षोडशहस्तः स्यान् मण्डपश्च चतुर्मुखः पूर्वद्वारे च संस्थाप्य बह्वृचं वेदपारगम् //
tathā ṣoḍaśahastaḥ syān maṇḍapaśca caturmukhaḥ pūrvadvāre ca saṃsthāpya bahvṛcaṃ vedapāragam //
Likewise, the maṇḍapa (pavilion) should measure sixteen cubits and be four-faced (open on four sides). At the eastern gateway one should station a Bahvṛca, a Ṛgvedic expert who has mastered the Veda.
This verse does not discuss Pralaya; it gives Vastuvidya guidance on mandapa measurement and the ritual placement of a Vedic expert at the eastern entrance.
It frames dharmic duty as correct patronage and supervision of sacred construction and rites—ensuring proper dimensions, orientation, and qualified Vedic officiants for public or household-sponsored worship.
Architecturally, it prescribes a sixteen-cubit, four-sided mandapa; ritually, it instructs placing a Ṛgvedic specialist (Bahvṛca) at the east gate, highlighting the auspicious and primary status of the eastern entrance.