Matsya Purana — Manvantaras
स्वामिना रक्ष्यमाणानाम् उत्सृष्टानां च सम्भ्रमे परस्वानाम् अनादानम् अलोभ इति संज्ञितम् //
svāminā rakṣyamāṇānām utsṛṣṭānāṃ ca sambhrame parasvānām anādānam alobha iti saṃjñitam //
Not taking what belongs to others—whether it is being guarded by its owner or has been left behind in a moment of confusion—is what is designated as non-greed (alobha).
It does not discuss Pralaya directly; it gives an ethical definition: during chaos or panic, one must still refrain from taking others’ property.
It frames alobha as a practical rule of conduct: a king must prevent looting during disorder, and a householder must not seize unclaimed-looking goods, even if they appear abandoned in confusion.
No Vastu or ritual procedure is stated; the takeaway is ethical restraint relevant to protecting property and social order, which indirectly supports stable civic life.