Matsya Purana — The Glory of Prayaga: Pilgrimage
ततो गत्वा प्रयागं तु सर्वदेवाभिरक्षितम् ब्रह्मचारी वसेन्मासं पितॄन्देवांश्च तर्पयेत् ईप्सितांल्लभते कामान् यत्र यत्राभिजायते //
tato gatvā prayāgaṃ tu sarvadevābhirakṣitam brahmacārī vasenmāsaṃ pitṝndevāṃśca tarpayet īpsitāṃllabhate kāmān yatra yatrābhijāyate //
Then, having gone to Prayāga—protected by all the gods—one should live there for a month as a brahmacārin (celibate student) and offer tarpana, libations of water, to the ancestors and the gods. Wherever such a person is reborn, he attains the desired enjoyments and fulfillments.
This verse does not address pralaya; it focuses on tirtha-mahātmya—how disciplined residence at Prayāga and offerings to devas and pitṛs generate merit that bears fruit across rebirths.
It frames a dharmic practice accessible to householders and rulers alike: undertaking a regulated vow (brahmacarya for a fixed period) and performing deva–pitṛ tarpana, reinforcing social-religious duties of honoring gods and ancestors.
The significance is ritual rather than architectural: residing at Prayāga under brahmacarya and performing tarpana (water-libations) to pitṛs and devas is presented as a high-merit observance tied to the sanctity of the confluence.