Matsya Purana — Genealogy and Classification of Sacred Fires
भृगोः प्रजायताथर्वा ह्य् अङ्गिराथर्वणः स्मृतः तस्य ह्य् अलौकिको ह्य् अग्निर् दक्षिणाग्निः स वै स्मृतः //
bhṛgoḥ prajāyatātharvā hy aṅgirātharvaṇaḥ smṛtaḥ tasya hy alaukiko hy agnir dakṣiṇāgniḥ sa vai smṛtaḥ //
From Bhṛgu was born Atharvan; he is remembered as Aṅgiras-Atharvan. Of him, the fire regarded as non-worldly (extraordinary) is indeed known as the Dakṣiṇāgni, the southern sacred fire.
Directly, it does not describe Pralaya; instead it preserves post-creation sacred lineage and ritual continuity by naming Atharvan’s descent and associating him with the Dakṣiṇāgni.
It supports dharmic duty through correct ritual knowledge: a householder (and a king who upholds Vedic order) maintains sacred fires and honors ṛṣi lineages, with Dakṣiṇāgni being one of the directionally defined fires in orthodox rites.
Ritually, it identifies Dakṣiṇāgni—the ‘southern fire’—implying directional placement in altar/household fire arrangements, a principle that also informs Vastu-style orientation of sacred spaces.