Matsya Purana — Solar–Lunar Motions
मुहूर्तैस्त्रिंशता तावद् अहोरात्रं भुवो भ्रमन् उभयोः काष्ठयोर्मध्ये भ्रमते मण्डलानि तु //
muhūrtaistriṃśatā tāvad ahorātraṃ bhuvo bhraman ubhayoḥ kāṣṭhayormadhye bhramate maṇḍalāni tu //
Thirty muhūrtas make up a day and night; and as the Earth turns, the celestial circles (orbital spheres) revolve between the two kāṣṭhās (time-divisions).
This verse does not directly describe pralaya; it focuses on kāla-māna (time-reckoning), defining the day-night cycle as thirty muhūrtas and linking it to the Earth’s turning and the motion of celestial ‘maṇḍalas’.
By defining the day-night measure (ahorātra) and its standard divisions, it supports correct scheduling of royal administration, vows, fasts, daily rites, and auspicious timing—key disciplines for both kings and householders in Purāṇic dharma.
Ritually, accurate muhūrta-based timing is essential for yajñas, consecrations, and temple ceremonies; while not giving Vāstu rules directly, it underpins the ‘muhūrta’ selection used in Puranic temple-building and installation rites.