Matsya Purana — The Legend of Acchodā: Pitṛloka
इत्युक्त्वा स गणस्तेषां तत्रैवान्तरधीयत साप्यवाप च तत्सर्वं फलं यदुदितं पुरा //
ityuktvā sa gaṇasteṣāṃ tatraivāntaradhīyata sāpyavāpa ca tatsarvaṃ phalaṃ yaduditaṃ purā //
Having spoken thus, that host of attendants vanished right there before them; and she too obtained in full that entire reward which had been declared earlier.
This verse does not discuss pralaya directly; it functions as a narrative closure emphasizing that the promised merit (phala) of a prior observance was truly attained.
It reinforces a key Purāṇic ethic: when prescribed dharmic acts are performed with faith, their stated results are believed to manifest—encouraging householders (and rulers) to uphold vows, gifts, and rituals consistently.
No specific Vāstu/temple rule is stated here; the ritual significance is the confirmation of phala—an assurance that the earlier-described rite or vow yields its promised outcome.