Matsya Purana — The Greatness of the Vibhūti-Dvādaśī Vow: Pushkara
उपविष्टस्त्वमेकस्मिन् सभार्यो भवनाङ्गणे अथ मङ्गलशब्दश्च त्वया रात्रौ महाञ्श्रुतः //
upaviṣṭastvamekasmin sabhāryo bhavanāṅgaṇe atha maṅgalaśabdaśca tvayā rātrau mahāñśrutaḥ //
While you were seated in one place, together with your wife, in the courtyard of your house, you then heard—at night—a great sound of auspiciousness.
Indirectly, it signals a portent-like “auspicious sound” preceding a significant turn in the narrative; the verse itself does not describe pralaya, but functions as an omen motif often used before major cosmic or historical events.
It places the listener in a gṛhastha setting—seated with his wife in the home courtyard—highlighting domestic order and attentiveness to dharmic signs; a ruler/householder is expected to be vigilant, discerning auspicious indications and responding with appropriate ritual or counsel-seeking.
The mention of the bhavanāṅgaṇa (house-courtyard) points to the domestic ritual space where auspicious sounds/benedictions are traditionally received; while not a technical Vastu rule, it aligns with Vastu Shastra usage of the courtyard as a central, ritually meaningful zone.