Om Namah Shivaya Gurave

This is a very ancient chant which encompasses some of the main, core teachings of yoga. It has been adopted by Anusara as it's primary invocation, chanted three times at the beginning of practice.

OM Namah Shivaya Gurave
Satchitananda Murtaye
Nisprapancaya Shantaya
Niralambaya Tejase

Meaning: (there can be many shades of meaning with sanskrit)
I bow to (Divine Consciousness) the true teacher within
I am pure awareness and at one with Source of all things
Forever expanding and fully peaceful
Depending on nothing else, I am radiant and powerful

When you hear the mantra Om Namah Shivaya being chanted, you can experience how natural and easy it is to chant the mantra, to be in the body of sound.  It is so easy for the mind to relax and let go.  You feel that you could continue chanting Om Namah Shivaya for hours.  You have no desire to do anything else because chanting this mantra will purify you, will give you a meditation, will give you the experience of the Divine, will give you just about everything.

~S. Chidvilasanada