Matsya Purana — Mandāra-Saptamī Vrata
इमामघौघपटलभीषणध्वान्तदीपिकाम् गच्छन्प्रगृह्य संसारे सर्वार्थांश्च लभेन्नरः //
imāmaghaughapaṭalabhīṣaṇadhvāntadīpikām gacchanpragṛhya saṃsāre sarvārthāṃśca labhennaraḥ //
In this worldly existence, the man who goes forth holding fast to this “lamp” that dispels the dreadful darkness formed by masses of sin, attains all desired aims.
It does not describe Pralaya directly; it uses the metaphor of “darkness” to depict the obscuring power of accumulated sin and presents a dharmic/ devotional means that illumines one’s path through saṃsāra.
For a king or householder engaged in worldly responsibilities, the verse teaches that steadfast adherence to a purifying dharmic practice (here likened to a lamp) removes moral obscurations and supports the attainment of legitimate goals (artha and other aims) without being overwhelmed by pāpa.
No Vāstu or temple-building rule is stated here; the “lamp” (dīpikā) is a spiritual metaphor for a protective recitation/teaching that dispels the darkness of sin.