उमामहेश्वरव्रतं—पञ्चाक्षरमन्त्रस्य माहात्म्यं, न्यासः, जपविधिः, सदाचारः, विनियोगः
आकारो नेत्रमस्त्रं तु यकारः परिकीर्तितः इत्थमङ्गानि विन्यस्य ततो वै बन्धयेद्दिशः
ākāro netramastraṃ tu yakāraḥ parikīrtitaḥ itthamaṅgāni vinyasya tato vai bandhayeddiśaḥ
The syllable “Ā” is declared to be the Netra-astra, the eye-weapon of protective awareness, and the syllable “Ya” is likewise taught as a mantra-limb. Having thus performed nyāsa upon the limbs, one should then bind the directions, securing the ritual space so the worship of Pati (Śiva) proceeds free from pāśa-born obstructions.
Suta Goswami (narrating Shiva-puja vidhi to the sages of Naimisharanya)