Matsya Purana — The Madana-Dvādaśī Vow and the Birth of the Maruts
फलमेकं च संप्राश्य द्वादश्यां भूतले स्वपेत् ततस्त्रयोदशे मासि धृतधेनुसमन्विताम् //
phalamekaṃ ca saṃprāśya dvādaśyāṃ bhūtale svapet tatastrayodaśe māsi dhṛtadhenusamanvitām //
Having eaten a single fruit, on Dvādaśī, the twelfth lunar day, one should sleep upon the ground. Then, on the Trayodaśī observance of that month, one should make the prescribed gift together with a cow duly prepared and ritually appointed.
This verse is not about Pralaya; it belongs to vrata-dharma, prescribing austerity (sleeping on the ground) and dana (gift-giving) on specific lunar days.
It outlines a householder-style discipline: restrained diet (one fruit), bodily austerity (ground-sleep), and charitable giving (cow-dana) timed to Dvādaśī–Trayodaśī, reflecting regulated living and support of dharma.
The significance is ritual rather than architectural: it gives a vrata sequence tied to lunar tithis and culminates in a formal dana involving a ritually prepared cow (dhenu) as part of the observance.