Matsya Purana — Narasimha’s Victory over Hiraṇyakaśipu and the Catalogue of Apocalyptic Omens
नद्यः ससागराः सर्वाः सो ऽकम्पयत दानवः कपिलश्च महीपुत्रो व्याघ्रवांश्चैव कम्पितः //
nadyaḥ sasāgarāḥ sarvāḥ so 'kampayata dānavaḥ kapilaśca mahīputro vyāghravāṃścaiva kampitaḥ //
That Dānava shook all the rivers together with the oceans; Kapila, the earth-born (son of the Earth), and Vyāghravāṃśa as well were set trembling.
It presents a classic pralaya-style portent: the natural order is destabilized—rivers and even oceans tremble—signaling an approaching cosmic crisis or transition.
As an omen-verse, it implies vigilance and dharmic preparedness: rulers and householders should respond to widespread disorder by strengthening protection, ritual steadiness, charity, and adherence to counsel from sages rather than panic.
No direct Vāstu rule is stated; however, the motif of “ground/realm trembling” functions as a ritual warning-sign—traditionally prompting śānti (pacificatory) rites before major undertakings such as consecrations or construction.