उमामहेश्वरव्रतं—पञ्चाक्षरमन्त्रस्य माहात्म्यं, न्यासः, जपविधिः, सदाचारः, विनियोगः
मन्त्रेण संस्पृशेद्देहं प्रणवेनैव संपुटम् मूर्ध्नि वक्त्रे च कण्ठे च हृदये गुह्यके तथा
mantreṇa saṃspṛśeddehaṃ praṇavenaiva saṃpuṭam mūrdhni vaktre ca kaṇṭhe ca hṛdaye guhyake tathā
With the prescribed mantra, one should ritually touch and consecrate the body; and, taking the Praṇava “Oṃ” as a sacred protective enclosure, apply it at the crown of the head, the face, the throat, the heart, and likewise at the secret place—thus establishing protective nyāsa for the worship of Pati, Lord Śiva.
Suta Goswami (narrating Shiva-puja procedure within the Linga Purana discourse)
It prescribes a preparatory nyāsa: consecrating the worshipper’s body with mantra and sealing it with Oṃ as a protective enclosure, making the practitioner fit (adhikārin) for Linga-pūjā.
By using the Pranava as the enclosing seal, the verse implies Śiva as Pati—the all-pervading consciousness that protects and purifies the pashu (individual soul) when approached through mantra and disciplined ritual.
Mantra-nyāsa with the Pranava-saṃpuṭa: touching specific bodily seats (crown, face, throat, heart, and guhyaka) to establish protection, concentration, and inner purification aligned with Shaiva sādhanā.