Om mani padme hum

Om mani padme hum is a six-syllabled Sanskrit mantra particularly associated Avalokiteshvara, the bodhisattva of compassion. It is in Tibetan Buddhism, the most ubiquitous mantra and the most popular form of religious practice, performed by laypersons and monastics alike.

Quotes

Om Mani Padme Hum, the sunrise comes!
The Dewdrop Slips Into The Shining Sea!
- Sir Edwin Arnold, The Light of Asia (1879)

We raise our hats to the hand a-moulding us
Sure 'nuff, he has the answer
He has the answer
He has the answer
be-duh-be-duh-be-duh-be-duh
Om mani padme
Om mani padme
Om mani padme hum.
- Kate Bush, in "Strange Phenomena" on The Kick Inside (1977)

It is very good to recite the mantra Om mani padme hum, but while you are doing it, you should be thinking on its meaning, for the meaning of the six syllables is great and vast. The first, 'Om is composed of three letters, A, U, and M. These symbolize the practitioner's impure body, speech, and mind; they also symbolize the pure exalted body, speech, and mind of a Buddha. Can impure body, speech, and mind be transformed into pure body, speech, and mind, or are they entirely separate? All Buddhas are cases of beings who were like ourselves and then in dependence on the path became enlightened; Buddhism does not assert that there is anyone who from the beginning is free from faults and possesses all good qualities. The development of pure body, speech, and mind comes from gradually leaving the impure states and their being transformed into the pure. How is this done? The path is indicated by the next four syllables.
- Tenzin Gyatso, the (14th Dalai Lama), in A Talk on OM MANI PADME HUM, Shambhala Publications, (Autumn 2002)