Shiva Purana — Vayaviya Samhita, Shloka 15
न्यासत्रैविध्य-भूतशुद्धि-प्रक्रिया
Threefold Nyāsa and the Procedure of Elemental Purification
देहस्यान्तः प्रविष्टं तं ध्यात्वा हृदयपंकजे । पुनश्चामृतवर्षेण सिंचेद्विद्यामयं वपुः । ततः कुर्यात्करन्यासं करशोधनपूर्वकम् । देहन्यासं ततः पश्चान्महत्या मुद्रया चरेत्
dehasyāntaḥ praviṣṭaṃ taṃ dhyātvā hṛdayapaṃkaje | punaścāmṛtavarṣeṇa siṃcedvidyāmayaṃ vapuḥ | tataḥ kuryātkaranyāsaṃ karaśodhanapūrvakam | dehanyāsaṃ tataḥ paścānmahatyā mudrayā caret
观想彼已入于身内、安住心莲之中者，当再以甘露之雨沐浴由真言所成之身。继而先净其手，行手安置（kara-nyāsa）。随后行身安置（deha-nyāsa），并以大印（mahā-mudrā）继续修持。
Suta Goswami (narrating the Vāyavīya teachings to the sages at Naimiṣāraṇya)
Tattva Level: pashu
Shiva Form: Dakṣiṇāmūrti
Role: teaching
FAQs
It teaches internalized Shaiva worship: Śiva is contemplated as the indwelling Lord in the heart-lotus, and the practitioner sanctifies the embodied self into a mantra-formed (vidyāmaya) instrument fit for grace (anugraha) and liberation.
Nyāsa and mudrā are supports for Saguna upāsanā: by installing mantra-power in hands and limbs, the devotee makes the body a living temple for Śiva, complementing external Linga worship with inner realization of the same Pati within.
Meditate on Śiva within the heart, visualize an amṛta-shower purifying the mantra-body, then perform hand purification, kara-nyāsa, deha-nyāsa, and conclude by applying the prescribed great mudrā.