Matsya Purana — Yadu Lineage
नष्टे धर्मे तथा जज्ञे विष्णुर्वृष्णिकुले प्रभुः कर्तुं धर्मस्य संस्थानम् असुराणां प्रणाशनम् //
naṣṭe dharme tathā jajñe viṣṇurvṛṣṇikule prabhuḥ kartuṃ dharmasya saṃsthānam asurāṇāṃ praṇāśanam //
When dharma had declined, the Lord Vishnu was born in the Vrishni lineage, in order to re-establish righteousness and to bring about the destruction of the asuras.
It does not describe pralaya directly; it presents a recurring Puranic principle that when cosmic order (dharma) collapses, Vishnu manifests to restore stability and remove destructive forces.
By framing dharma as something that can decline and must be re-established, the verse supports the Matsya Purana’s broader ethic that rulers and householders should protect social-religious order—restraining harmful forces and upholding righteous conduct in their spheres.
No explicit Vastu or temple-ritual rule appears in this verse; its ritual takeaway is theological—dharma-restoration is the aim of worship and observance, aligning practice with the protection of sacred order.