Matsya Purana — Saptamī Sacred Bath and the Mṛtavatsābhiṣeka Rite for Pacifying Misfortune an...
सप्तमीस्नपनं वक्ष्ये सर्वलोकहिताय वै जातस्य मृतवत्सायाः सप्तमे मासि नारद अथवा शुक्लसप्तम्याम् एतत्सर्वं प्रशस्यते //
saptamīsnapanaṃ vakṣye sarvalokahitāya vai jātasya mṛtavatsāyāḥ saptame māsi nārada athavā śuklasaptamyām etatsarvaṃ praśasyate //
I shall explain the Saptamī bathing rite (Saptamī-snapana), intended for the welfare of all people. O Nārada, it is especially commended for a woman who has given birth to a dead child—either in the seventh month, or on the bright fortnight’s seventh lunar day; all of this is considered highly praiseworthy.
This verse does not discuss Pralaya; it focuses on a ritual bathing observance (Saptamī-snapana) and its recommended timing for purification and well-being.
It supports the householder’s dharma by prescribing a specific purificatory rite and auspicious timing, especially addressing ritual well-being after an inauspicious birth outcome, reinforcing social and personal religious duty.
The significance is ritual (not architectural): it commends the Saptamī bathing rite, particularly for a woman who has suffered a stillbirth/infant loss, to be performed in the seventh month or on Śukla Saptamī.