Matsya Purana — Glory of Tīrtha-Śrāddha: Best Times
प्रातःकालो मुहूर्तांस् त्रीन् संगवस् तावदेव तु मध्याह्नस्त्रिमुहूर्तः स्याद् अपराह्णस्ततः परम् //
prātaḥkālo muhūrtāṃs trīn saṃgavas tāvadeva tu madhyāhnastrimuhūrtaḥ syād aparāhṇastataḥ param //
The morning consists of three muhūrtas; the forenoon (saṅgava) is of the same duration. Midday comprises three muhūrtas, and thereafter comes the afternoon (aparāhṇa).
This verse does not discuss pralaya; it defines practical divisions of daytime into muhūrtas used for ritual and disciplined living.
It supplies a time-framework for scheduling daily rites (sandhyā, pūjā, charity, judicial/administrative work), helping kings and householders align actions with prescribed periods of the day.
Muhūrta-based day divisions are foundational for selecting auspicious times (muhūrta) for rites and for Vastu/temple activities such as ground-breaking, installation, and consecration.