Matsya Purana — Glory of Prayaga: The Fruit of the Anashaka Fast and the Merit of the Yamuna
व्यतीतान्पुरुषान्सप्त भविष्यांश्च चतुर्दश नरस्तारयते सर्वान् यस्तु प्राणान्परित्यजेत् //
vyatītānpuruṣānsapta bhaviṣyāṃśca caturdaśa narastārayate sarvān yastu prāṇānparityajet //
A man who gives up his life (for the sake of this dharma) delivers them all—seven generations of forefathers who have passed away, and fourteen generations yet to come.
It does not describe Pralaya directly; it teaches the trans-generational spiritual effect of a supreme act of dharma—one person’s sacrifice can ‘carry across’ ancestors and descendants.
It frames Pitṛ-dharma as a high duty: a householder (and by extension a king as protector of dharma) should uphold rites and ethical sacrifices that sustain family lines and benefit ancestors, emphasizing responsibility beyond one lifetime.
The significance is ritual (not architectural): it highlights the fruit of Śrāddha/Pitṛ-related dharma—ancestral deliverance across specified generations—often cited to stress careful performance of ancestor rites.