Matsya Purana — Origin of Soma
ततः पद्मसहस्राणां सहस्राणि दशैव तु तपश्चचार शीतांशुर् विष्णुध्यानैकतत्परः //
tataḥ padmasahasrāṇāṃ sahasrāṇi daśaiva tu tapaścacāra śītāṃśur viṣṇudhyānaikatatparaḥ //
Thereafter, Śītāṃśu performed austerities for ten thousand thousands of lotus-counted years, wholly devoted to nothing but meditation upon Viṣṇu.
Directly, it does not describe pralaya; it highlights the Purāṇic ideal that immense cosmic time spans are devoted to tapas and Viṣṇu-dhyāna, implying that spiritual merit and divine meditation operate across vast aeons that frame creation and dissolution cycles.
It models ekāgratā (single-pointed devotion) and disciplined practice: for kings and householders in the Matsya Purana’s ethical spirit, this translates into steady observance of dharma—daily worship, vows, self-restraint, and sustained commitment rather than sporadic piety.
No Vāstu or iconographic rule is stated; the ritual takeaway is the primacy of Viṣṇu-dhyāna and tapas as core sādhana—an inner ‘ritual’ that complements external rites and temple worship.