This mantra is present in the Shri Rudram hymn which is part of the Krishna Yajurveda. Shri Rudram hymn is taken from two chapters in fourth book of Taittiriya Samhita (TS 4.5, 4.7) of Krishna Yajurveda. Each chapter consist of eleven anuvaka or hymns. Name of both chapters are Namakam (chapter five) and Chamakam (chapter seven) respectively. The mantra appears without the initial Om in the eighth hymn of Namakam(TS 4.5.8.1) as Namaḥ śivāya ca śivatarāya ca (Sanskrit: नमः शिवाय च शिवतराय च). This means “Salutations unto Śiva the auspicious one, unto Śivatara the one than whom none more auspicious can exist

In different scriptures

1. The Mantra appears as ‘Na’ ‘Ma’ ‘Śi’ ‘Vā’ and ‘Ya’ in the Shri Rudram hymn which is a part of the Krishna Yajurveda. Thus predates the use of Shiva as a proper name, in the original context being an address to Lord Rudra (later Shiva), where Shiva retains its original meaning as an adjective, meaning “auspicious, benign, friendly”, a euphemistic epithet of Rudra.
2. The mantra appears in the Rudrashtadhyayi which is a part of the Shukla Yajurveda.
3. Whole Panchakshara Stotra is dedicated to this mantra.
4. Tirumantiram, a scripture written in Tamil language, speaks of the meaning of the mantra.
5. It appears in the Shiva Purana in the chapter 1.2.10 (Shabda-Brahma Tanu) and in its Vidyeshvara samhita and in chapter 13 of the Vayaviya samhita of the Shiva Purana as ‘Om Namaha Shivaya’.
6. The Tamil Saivaite hymn Tiruvacakam begins with the five letters ‘Na’ ‘Ma’ ‘Śi’ ‘Vā’ and ‘Ya’.

Usage

This mantra is repeated verbally or mentally, drawing the mind in upon itself to Lord Shiva’s infinite, all-pervasive presence. Traditionally it is repeated 108 times a day while keeping count on a strand of rudraksha beads. This practice is called japa yoga. It is freely sung and chanted by everyone, but it is most powerful when given by one’s guru. Before this initiation which is called mantra diksha, the guru will usually require a period of study. This initiation is often part of a temple ritual, such as a puja, japa, homa (fire ceremony), dhyana or and while smearing vibhuti. The guru whispers the mantra into the disciple’s right ear, along with instructions on how and when to chant it.

Intended effect

This mantra is associated with qualities of prayer, divine-love, grace, truth, and blissfulness. When done correctly, it calms the mind and brings spiritual insight and knowledge. It also keeps the devotee close to Shiva and within His protective global fellowship.

Traditionally, it is accepted to be a powerful healing mantra beneficial for all physical and mental ailments. Soulful recitation of this mantra brings peace to the heart and joy to the Ātman or soul. Many Hindu teachers consider that the recitation of these syllables is sound therapy for the body and nectar for the Ātman. The nature of the mantra is the calling upon the higher self; it is the calling upon Shiva.

Contemporary developments

The mantra has gained wider use outside India as a result of Siddha Yoga, founded by Swami Muktananda, in which it is the main mantra used for meditation and chanting.

In the film Eat, Pray, Love: One Woman’s Search for Everything Across Italy, India and Indonesia (2007), Elizabeth Gilbert explained that the first chant provided by her guru was “Om Namah Shivaya.”Gilbert wrote that this meant “I honor the divinity within me