Matsya Purana — Origin of Soma
तद्दीप्तिरधिका तस्माद् रात्रौ भवति सर्वदा तेनौषधीशः सोमो ऽभूद् द्विजेशश्चापि गद्यते //
taddīptiradhikā tasmād rātrau bhavati sarvadā tenauṣadhīśaḥ somo 'bhūd dvijeśaścāpi gadyate //
Therefore his radiance is always greater at night; for that reason Soma (the Moon) became the lord of medicinal herbs, and is also praised as the chief among the twice-born (dvija).
This verse is not directly about Pralaya; it explains a cosmic function of Soma (the Moon)—his night-brightness and his role as the lord of herbs—within the Purana’s broader cosmological teaching.
Indirectly, it supports dharmic living by grounding ritual and daily life in cosmic order: the householder’s timing of rites (night observances, Soma-related worship) and the king’s duty to protect health and agriculture align with Soma’s governance over herbs and nourishment.
Ritually, Soma’s identification as Auṣadhīśa supports Soma/Chandra worship and the sanctity of herbs used in yajña, āyurvedic preparations, and consecrations; there is no explicit Vāstu or temple-measure rule stated in this verse.