Matsya Purana — Ila–Sudyumna Episode and the Expansion of the Ikṣvāku
खनन्तः पृथिवीं दग्धा विष्णुना ये ऽश्वमार्गणे असमञ्जसस्तु तनयो यो ऽंशुमान्नाम विश्रुतः //
khanantaḥ pṛthivīṃ dagdhā viṣṇunā ye 'śvamārgaṇe asamañjasastu tanayo yo 'ṃśumānnāma viśrutaḥ //
While digging up the earth in search of the Aśvamedha sacrificial horse, those sons of Sagara were burned by Viṣṇu (in the form of Kapila). But Asamañjasa had a son renowned as Aṃśumān.
This verse does not describe Pralaya; it belongs to a dynastic narrative, highlighting divine intervention (burning by Viṣṇu/Kapila) during Sagara’s Aśvamedha horse search.
It reflects the royal pursuit of sovereignty through Aśvamedha and implies ethical caution: even kingly enterprises can incur catastrophic consequences when driven by excessive force—yet rightful succession continues through a worthy heir (Aṃśumān).
The ritual reference is Aśvamedha (horse-sacrifice), a major royal rite tied to kingship and legitimacy; no Vāstu or temple-architecture rule is stated in this verse.