Matsya Purana — Bhīma-Dvādaśī
ततः पुण्यां तिथिमिमां सर्वपापप्रणाशिनीम् उपोष्य विधिनानेन गच्छ विष्णोः परं पदम् //
tataḥ puṇyāṃ tithimimāṃ sarvapāpapraṇāśinīm upoṣya vidhinānena gaccha viṣṇoḥ paraṃ padam //
Thereafter, by fasting on this sacred lunar day—which destroys all sins—according to this prescribed method, you shall go to Viṣṇu’s supreme abode.
This verse does not describe pralaya directly; it teaches a dharmic means (fasting on a purifying tithi) that leads beyond sin toward Viṣṇu’s supreme state.
It frames vrata and upavāsa as practical duties for disciplined living—by observing a sacred tithi according to rule, a householder or ruler purifies wrongdoing and aligns governance and personal life with dharma.
The significance is ritual rather than architectural: proper observance of a tithi-based fast (upavāsa) “according to method” is emphasized as the efficacious procedure leading to spiritual attainment.