Matsya Purana — Measures of Time: Caturyuga Computation
अहोरात्रे विभजते सूर्यो मानुषलौकिके रात्रिः स्वप्नाय भूतानां चेष्टायै कर्मणामहः //
ahorātre vibhajate sūryo mānuṣalaukike rātriḥ svapnāya bhūtānāṃ ceṣṭāyai karmaṇāmahaḥ //
In the human world, the Sun apportions time into day and night: night is for the sleep of beings, and day is for activity and the performance of duties.
It does not describe Pralaya directly; it explains the orderly cosmic function of the Sun in regulating human time—day for action and night for rest—reflecting sustained cosmic order rather than dissolution.
It supports dharmic time-discipline: a householder (and a king) should align work, governance, rituals, and responsibilities with daytime activity, while reserving night primarily for rest—promoting effective, righteous conduct.
No direct Vastu or temple rule is stated, but the principle underlies ritual scheduling: many rites and daily observances are prescribed by day/night divisions governed by Surya’s timekeeping.