Matsya Purana — Soma
अत्र देवान्पितॄंश्चैते पितरो लौकिकाः स्मृताः तेषां ते धर्मसामर्थ्यात् स्मृताः सायुज्यगा द्विजैः //
atra devānpitṝṃścaite pitaro laukikāḥ smṛtāḥ teṣāṃ te dharmasāmarthyāt smṛtāḥ sāyujyagā dvijaiḥ //
Here, these are remembered as the worldly Pitṛs—ancestors among the gods and among the manes. By the power of their dharma, the learned twice-born declare that they attain sāyujya (union or close communion) with the divine.
This verse is not about pralaya; it explains the status of certain Pitṛs (ancestors) and states that through the strength of dharma they are said to attain sāyujya—an exalted posthumous union/communion with the divine.
It supports the householder’s (and ruler’s) duty to uphold dharma and maintain ancestral rites (Śrāddha), implying that dharmic merit connected with Pitṛ obligations leads to elevated ancestral states such as sāyujya.
The significance is ritual rather than architectural: it frames Pitṛ doctrine used to justify Śrāddha/ancestor-offerings, emphasizing that dharma linked to such rites yields high spiritual attainments for the ancestors.