Matsya Purana — Solar–Lunar Motions
मध्याह्नस्त्रिमुहूर्तस्तु तस्मात्कालादनन्तरम् तस्मान्मध्यंदिनात्कालाद् अपराह्ण इति स्मृतः //
madhyāhnastrimuhūrtastu tasmātkālādanantaram tasmānmadhyaṃdinātkālād aparāhṇa iti smṛtaḥ //
Midday (madhyāhna) comprises three muhūrtas; immediately following that time, the period after midday is traditionally remembered as aparāhṇa (the afternoon).
This verse does not discuss pralaya; it defines practical divisions of daytime (midday and the following afternoon) used for regulating ritual and daily observances.
By defining madhyāhna and aparāhṇa precisely, it supports dharma-based scheduling—kings and householders can time donations, audience, worship, and domestic rites according to proper daytime periods.
It provides a time-classification framework used in ritual manuals and Vastu-related practice for choosing appropriate hours (muhūrtas) for rites such as pūjā, homa, consecrations, and other regulated ceremonies.