उमामहेश्वरव्रतं—पञ्चाक्षरमन्त्रस्य माहात्म्यं, न्यासः, जपविधिः, सदाचारः, विनियोगः
अङ्गन्यासं न्यसेत्पश्चाद् एष साधारणो विधिः ओङ्कारं संपुटीकृत्य सर्वाङ्गेषु च विन्यसेत्
aṅganyāsaṃ nyasetpaścād eṣa sādhāraṇo vidhiḥ oṅkāraṃ saṃpuṭīkṛtya sarvāṅgeṣu ca vinyaset
Thereafter, one should perform aṅga-nyāsa (the placement of mantra-power upon the limbs). This is the common, standard procedure. Enclosing the practice with the syllable Oṃ as a protective seal, one should then place it upon all the limbs—so that the body becomes a sanctified seat for Śiva’s mantra.
Suta Goswami (narrating the Linga-puja vidhi to the sages of Naimisharanya)
It teaches the prerequisite inner consecration for Linga-puja: by aṅga-nyāsa and sealing with Oṃ, the sādhaka makes the body a fit vessel for Śiva-mantra before external offerings.
Śiva-tattva is approached here as mantra-presence (Pati) that can be installed within the embodied pashu; when the limbs are permeated by mantra, bondage (pāśa) is weakened through sanctified awareness.
Aṅga-nyāsa and mantra-vinyāsa, with Oṃ as a protective saṃpuṭa (seal), a core preparatory discipline aligned with Pāśupata-style mantra-sādhana and ritual purity.