Matsya Purana — Hiranyakashipu’s Boons
न चास्त्रेण न शस्त्रेण गिरिणा पादपेन च न शुष्केण न चार्द्रेण न दिवा न निशाथ वा //
na cāstreṇa na śastreṇa giriṇā pādapena ca na śuṣkeṇa na cārdreṇa na divā na niśātha vā //
“Neither by a missile nor by a weapon; neither by a mountain nor by a tree; neither by what is dry nor by what is wet; neither by day nor yet by night—(may he be slain) by none of these.”
It highlights the Purāṇic motif that even seemingly absolute protections are bounded by cosmic law; in pralaya-linked storytelling, such “invulnerability clauses” show how order is restored without violating stated conditions.
It implies that power and security are never absolute; a king or householder should govern and live by dharma rather than rely on boons, force, or technical protections, since moral order ultimately prevails.
No direct Vāstu or ritual rule is stated; the verse is a narrative-legal formula about the permitted/forbidden modes of death, often used to set up a dharmic resolution through a “loophole” (e.g., neither day nor night).