Matsya Purana — The Madana-Dvādaśī Vow and the Birth of the Maruts
तस्मात्त्वमनया वृत्त्या गर्भे ऽस्मिन्यत्नमाचर स्वस्त्यस्तु ते गमिष्यामि तथेत्युक्तस्तया पुनः //
tasmāttvamanayā vṛttyā garbhe 'sminyatnamācara svastyastu te gamiṣyāmi tathetyuktastayā punaḥ //
Therefore, you should strive by this very discipline within this womb-like enclosure. May auspiciousness be yours; I shall depart. Addressed again by her in this manner, he replied, “So be it.”
It reflects a survival-and-protection motif within the Pralaya episode: the instructed person is told to persist with disciplined effort inside a protective “womb-like” enclosure, implying preservation through dissolution.
The verse emphasizes steady, methodical conduct (vṛtti) and diligent effort (yatna) even under crisis—an ethical ideal applicable to rulers and householders in Purāṇic dharma: maintain right practice and composure when circumstances are unstable.
While not a Vāstu rule, the term “garbha” evokes the idea of a protected inner chamber (garbha-gṛha imagery by association); the main takeaway is symbolic containment/preservation rather than explicit temple-architecture instruction.