Matsya Purana — Inquiry into Yayāti’s Story and the Kacha–Devayānī Episode
रक्षते दानवांस्तत्र न स रक्षत्यदानवान् तम् आराधयितुं शक्तो नान्यः कश्चिदृते त्वया //
rakṣate dānavāṃstatra na sa rakṣatyadānavān tam ārādhayituṃ śakto nānyaḥ kaścidṛte tvayā //
There he protects the Dānavas, but he does not protect those who are not Dānavas. None other than you is able to propitiate him and win his favor.
This verse does not discuss Pralaya; it focuses on selective protection in a conflict setting and the unique capacity of the addressed person to propitiate the protector.
It reflects a political-ethical theme: protection may be factional, and a capable leader (such as Manu in Purāṇic framing) is urged to negotiate/propitiate a powerful ally for broader security.
No Vāstu or temple-building rule is stated; the ritual takeaway is the idea of ārādhana (propitiation) as a means to secure protection or favor.