Matsya Purana — Solar Dynasty Prelude: Vivasvān–Saṃjñā–Chāyā
दस्रौ सुतत्वात् संजातौ नासत्यौ नासिकाग्रतः ज्ञात्वा चिराच्च तं देवं संतोषम् अगमत् परम् //
dasrau sutatvāt saṃjātau nāsatyau nāsikāgrataḥ jñātvā cirācca taṃ devaṃ saṃtoṣam agamat param //
Because they were born as sons, the two renowned ones—Dasra and Nāsatya—came forth from the tip of the nose. And, after a long time, having recognized that deity, he attained the highest contentment.
This verse does not describe Pralaya; it presents a mythic origin detail about the Aśvins (Dasra and Nāsatya) and emphasizes recognition of the divine leading to supreme contentment.
Indirectly, it highlights a core ethical idea used throughout the Matsya Purana: right knowledge/recognition of the divine (jñātvā taṃ devaṃ) culminates in inner satisfaction (saṃtoṣa), a virtue praised for rulers and householders as a stabilizing dharmic quality.
No Vastu or temple-building rule is stated here; the verse is primarily mythological/theological, though the Aśvins are widely associated in ritual culture with healing and auspicious invocations.