Matsya Purana — Yadu Lineage
एवमुक्ताब्रवीदेनं तपसा ज्ञातुमर्हसि चिकीर्षितं हि मे ब्रह्मंस् त्वं हि वेत्थ यथातथम् //
evamuktābravīdenaṃ tapasā jñātumarhasi cikīrṣitaṃ hi me brahmaṃs tvaṃ hi vettha yathātatham //
Thus addressed, he said to him: “O Brahman, you are fit to know through austerity what I intend to accomplish; for you indeed know it truly, just as it is.”
It indicates that the coming events (often read within the Pralaya framework) are part of a deliberate divine intention, and that such knowledge is accessed through tapas and true insight.
It models the ideal of disciplined inquiry: a ruler like Manu is expected to seek right understanding through self-restraint (tapas) and alignment with truth, before acting on momentous responsibilities.
No direct Vastu or temple-rule detail appears; the ritual principle implied is that tapas (austerity/observance) is a valid means for receiving authoritative knowledge for correct action.