Matsya Purana — The Attendant Hosts of the Sun and Moon: Monthly Gaṇas
विद्युत्सूर्यश्च तावुग्रौ यातुधानौ तु तौ स्मृतौ सहे चैव सहस्ये च वसन्त्येते दिवाकरे //
vidyutsūryaśca tāvugrau yātudhānau tu tau smṛtau sahe caiva sahasye ca vasantyete divākare //
Vidyutsūrya and (another named) Sūrya—those two are remembered as fierce yātudhānas (demonic beings). They dwell in the Sun during the months of Sahā and Sahasya.
This verse is not about Pralaya; it belongs to cosmological time-keeping, describing specific beings (yātudhānas) associated with the Sun during particular solar months.
Indirectly, it supports dharma through correct calendrical knowledge—knowing the solar months and their cosmic associations helps a king or householder time rituals, vows, and public ceremonies according to the sacred calendar.
No Vāstu rule is stated here; the ritual takeaway is calendrical—Sahā and Sahasya are highlighted as months whose solar association is described, useful for scheduling saṃskāras and observances in a Jyotiṣa-informed way.