Matsya Purana — Measures of Time: Caturyuga Computation
इतरेषु ससंध्येषु ससंध्यांशेषु च त्रिषु एकपादे निवर्तन्ते सहस्राणि शतानि च //
itareṣu sasaṃdhyeṣu sasaṃdhyāṃśeṣu ca triṣu ekapāde nivartante sahasrāṇi śatāni ca //
In the other three yugas as well, together with their sandhyā junctions and sandhyāṃśa portions, the amounts reckoned in thousands and hundreds are reduced to a single quarter (ekapāda) alone.
This verse is not about Pralaya; it addresses ritual time-junctions (Sandhyā) and states that outside the prime junction, the spiritual yield is diminished to a quarter.
It reinforces nitya-karma discipline: a householder (and by extension a king setting public dharma) should perform Sandhyā at the proper junction-time, since doing it in secondary portions yields only a fraction of the intended merit.
Ritual significance: it is a timing rule for Sandhyā observance, implying that correct temporal alignment (the Sandhyā ‘junction’) is essential for full efficacy; otherwise the result is reduced to one quarter.