Matsya Purana — Glory of Tīrtha-Śrāddha: Best Times
यः प्रयाति स पूतात्मा नारायणपदं व्रजेत् कृतशौचं महापुण्यं सर्वपापनिषूदनम् //
yaḥ prayāti sa pūtātmā nārāyaṇapadaṃ vrajet kṛtaśaucaṃ mahāpuṇyaṃ sarvapāpaniṣūdanam //
Whoever departs thus becomes pure in spirit and goes to the abode of Nārāyaṇa; having performed the proper purifications, one gains great merit and destroys all sins.
This verse is not describing Pralaya directly; it emphasizes personal purification (śauca) and the soul’s post-death destiny—attainment of Nārāyaṇa’s abode—rather than cosmic dissolution.
It frames śauca (cleanliness and purificatory observances) as a core dharmic duty: a householder—and by extension a king who models dharma—should uphold purity in conduct and rites, which is said to yield great merit and remove sin.
The ritual significance is śauca: the completion of purificatory cleanliness/rites is presented as spiritually efficacious, leading to great puṇya and the eradication of sin; there is no explicit Vāstu or temple-architecture rule in this verse.