Matsya Purana — Glory of Tīrtha-Śrāddha: Best Times
ऊर्ध्वं मुहूर्तात्कुतपाद् यन्मुहूर्तचतुष्टयम् मुहूर्तपञ्चकं चैतत् स्वधाभवनमिष्यते //
ūrdhvaṃ muhūrtātkutapād yanmuhūrtacatuṣṭayam muhūrtapañcakaṃ caitat svadhābhavanamiṣyate //
The four muhūrtas following the Kutapa-muhūrta—making five muhūrtas in all—are regarded as the ‘abode of Svadhā’, the proper time for offerings to the Ancestors.
This verse is not about Pralaya; it is a dharma-ritual instruction defining a sacred time-window (muhūrta set) specifically suited to Pitṛ offerings marked by the formula ‘svadhā’.
It guides the gṛhastha (and also a king as chief householder) to perform śrāddha and Pitṛ-yajña at the ritually proper time—after Kutapa—so that ancestor offerings are considered correctly placed and efficacious.
The significance is ritual (not architectural): it identifies the ‘Svadhā-bhavana’ period—five muhūrtas including Kutapa and the four following—as the appropriate timing for ancestor rites and related offerings.