Matsya Purana — Hiranyakashipu’s Boons
साहाय्यं च महाबाहुर् ओंकारं गृह्य सत्वरम् अथौंकारसहायस्तु भगवान्विष्णुरव्ययः //
sāhāyyaṃ ca mahābāhur oṃkāraṃ gṛhya satvaram athauṃkārasahāyastu bhagavānviṣṇuravyayaḥ //
And, O mighty-armed one, swiftly take the syllable Oṃ as your aid; for with Oṃ as his support, the Blessed Lord Viṣṇu—imperishable—(becomes the unfailing helper).
Indirectly, it points to the imperishable (avyaya) nature of Viṣṇu—an anchor beyond cosmic change—implying that Oṃ is a stabilizing refuge even when worlds undergo dissolution.
It recommends immediate reliance on Oṃ as spiritual support—practical guidance for rulers and householders to steady the mind, invoke divine protection, and act decisively with dharmic clarity.
Ritually, it elevates Oṃ as a primary supportive mantra (aid) in invocation; it can be understood as a core praṇava used at the start of rites, recitations, and protective prayers rather than a Vāstu/temple-measurement rule.