Matsya Purana — Manvantaras
तस्मात्स्मार्तः सूतो धर्मो वर्णाश्रमविभागशः एवं वै द्विविधो धर्मः शिष्टाचारः स उच्यते //
tasmātsmārtaḥ sūto dharmo varṇāśramavibhāgaśaḥ evaṃ vai dvividho dharmaḥ śiṣṭācāraḥ sa ucyate //
Therefore, the Smārta (scripture-based) dharma is taught as being apportioned according to the divisions of varṇa and āśrama. Thus, dharma is indeed of two kinds; the second is called the conduct (ācāra) of the cultured and disciplined (śiṣṭas).
This verse is not about Pralaya; it classifies dharma as (1) Smārta, regulated by varṇa and āśrama divisions, and (2) śiṣṭācāra, the exemplary conduct of the learned.
It grounds duties in varṇāśrama—so a householder or king should follow Smṛti-prescribed obligations appropriate to their station, and also uphold śiṣṭācāra: the recognized standards of good conduct practiced by the wise, which guides practical governance and daily ethics.
No direct Vāstu or iconographic rule appears here; the ritual takeaway is that correct practice is validated both by Smṛti injunctions and by śiṣṭācāra (accepted, exemplary custom) when applying dharma in real rites and social life.