Om Namah Shivaya is at the center from the Vedas and Tantras (historical Scriptures) and finds its mention while in the Yajurveda from the Shri Rudram hymn. Perceived to become most successful if, while in the exercise of Japa Yoga, wherever the mantra is recurring verbally or mentally 108 periods https://directorylandia.com/listings584889/the-2-minute-rule-for-10-most-powerful-mantra