Matsya Purana — The Kauśika Descendants: Śrāddha
राज्यकामो ऽभवच्चैकस् तेषां मध्ये जलौकसाम् पितृवर्ती च यो विप्रः श्राद्धकृत् पितृवत्सलः //
rājyakāmo 'bhavaccaikas teṣāṃ madhye jalaukasām pitṛvartī ca yo vipraḥ śrāddhakṛt pitṛvatsalaḥ //
Among those water-dwelling beings, one alone became desirous of sovereignty; and there was also a brāhmaṇa—devoted to the ways of the Fathers—who performed śrāddha and was affectionate toward the Pitṛs.
This verse does not directly describe pralaya; it instead highlights moral tendencies (desire for rulership) and the counterbalancing virtue of Pitṛ-dharma through śrāddha.
It contrasts ambition for sovereignty with the dharmic ideal of a householder-brāhmaṇa who faithfully performs śrāddha and maintains devotion to the ancestors—implying that social order and legitimacy rest on ritual duty and reverence for lineage.
The ritual significance is explicit: performing śrāddha (ancestral rite). No Vāstu or temple-architecture rule is stated in this verse.