Milarepa Mantra

Full Form:

Oṃ Āḥ Guru Hasavajra Sarvasiddhi Hum

Meaning:

Guru = Teacher
Hasa = Laughing
Vajra = Thunderbolt or Diamond
Sarvasiddhi = All accomplished or All accomplishing
Hum = Wisdom

Milarepa is known as the Laughing Vajra or Hevajra, and finds spiritual enlightenment through listening.