Matsya Purana — Bhīma-Dvādaśī
अशेषदुष्टशमनम् अशेषसुरपूजितम् पवित्राणां पवित्रं च मङ्गलानां च मङ्गलम् भविष्यं च भविष्याणां पुराणानां पुरातनम् //
aśeṣaduṣṭaśamanam aśeṣasurapūjitam pavitrāṇāṃ pavitraṃ ca maṅgalānāṃ ca maṅgalam bhaviṣyaṃ ca bhaviṣyāṇāṃ purāṇānāṃ purātanam //
It removes all wickedness and is revered by all the gods; it is the purest among purifiers and the most auspicious among auspicious things. It is the “future” even of all that is yet to come, and the most ancient among the Purāṇas.
Directly, it does not describe Pralaya; instead it frames the Purana itself as a timeless authority—“ancient among the Puranas” and relevant even for what is yet to come—supporting its role as a guide across cycles of creation and dissolution.
By presenting the Purana as the supreme purifier and destroyer of wickedness, it implies that rulers and householders should study/hear such teachings to cultivate dharma, restrain wrongdoing, and establish auspicious order in personal and public life.
No specific Vastu or iconographic rule is stated; the ritual takeaway is that recitation/hearing of the Purana is itself treated as highly auspicious and purificatory, suitable as a sanctifying component in rites and observances.