उमामहेश्वरव्रतं—पञ्चाक्षरमन्त्रस्य माहात्म्यं, न्यासः, जपविधिः, सदाचारः, विनियोगः
पादयोर् उभयोश्चैव गुह्ये च हृदये तथा कण्ठे च मुखमध्ये च मूर्ध्नि च प्रणवादिकम्
pādayor ubhayoścaiva guhye ca hṛdaye tathā kaṇṭhe ca mukhamadhye ca mūrdhni ca praṇavādikam
One should place the Praṇava “Oṃ”—and the sacred formulae beginning with it—upon both feet, upon the secret region, upon the heart, upon the throat, in the middle of the mouth, and upon the crown of the head. Thus, through nyāsa, the body is consecrated as a seat of Pati (Śiva).
Suta Goswami (narrating Purāṇic teaching to the sages of Naimiṣāraṇya; presenting a Śaiva nyāsa-vidhi)
It teaches internal Linga-worship through nyāsa: by installing Om in key bodily centers, the sādhaka consecrates the body as Śiva’s abode, aligning outer pūjā with inner realization.
Śiva as Pati is approached as the indwelling Lord accessible through the Pranava; the verse implies that Śiva’s presence can be ritually and contemplatively स्थापित (installed) in the embodied field of the pashu, loosening pāśa through mantra-awareness.
Pranava-nyāsa (deha-nyāsa): touching/mentally placing Om and related mantras on feet, guhya, heart, throat, mouth-center, and crown—supporting Pāśupata-style mantra-yoga and purification before Śiva-pūjā.