Matsya Purana — The Attendant Hosts of the Sun and Moon: Monthly Gaṇas
यातुधानस्तथा हेतिर् व्याघ्रश्चैव तु तावुभौ नभस्यनभसोरेतैर् वसन्तश्च दिवाकरे //
yātudhānastathā hetir vyāghraścaiva tu tāvubhau nabhasyanabhasoretair vasantaśca divākare //
Likewise, Yātudhāna and Heti—and also Vyāghra—these pairs are associated with the months Nabhasya and Nabhas; and they are connected with Vasanta (the spring season) and with Divākara (the Sun).
This verse is not about Pralaya; it belongs to a calendrical/cosmological listing that links named beings with months, seasons, and the Sun.
Indirectly, it supports dharmic timekeeping: knowing months/seasons and solar cycles helps schedule rites, vows, agriculture, and royal/household observances according to the Hindu calendar.
No Vāstu rule is stated; the ritual takeaway is calendrical—months (Nabhasya/Nabhas), season (Vasanta), and the Sun (Divākara) are invoked as time-markers for properly timing ceremonies and observances.