Matsya Purana — The Greatness and Procedure of the Aṅgāra
स कदाचिद्भवांस्तस्य पूजार्घ्यादिकमुत्तमम् दृष्टवान्क्रियमाणं च शूद्रेण च व्यवस्थितः //
sa kadācidbhavāṃstasya pūjārghyādikamuttamam dṛṣṭavānkriyamāṇaṃ ca śūdreṇa ca vyavasthitaḥ //
Once, you happened to see his excellent acts of worship—such as the offering of arghya and the like—being performed, duly arranged, by a Śūdra.
This verse does not address pralaya directly; it focuses on an observed act of worship (pūjā) and the proper performance of offerings like arghya.
It highlights attentive observation of correct ritual performance—relevant to householders and rulers who are expected to uphold dharma by ensuring worship is conducted properly and respectfully within their domain.
Ritually, it emphasizes pūjā procedures, specifically arghya and allied offerings, being 'vyavasthita'—properly arranged—an idea that aligns with orderly ritual setup (often discussed alongside temple/altar arrangement in Purāṇic practice).