Padmasambhava's famous mantra, "Om Ah Hum Vajra Guru Padma Siddhi Hum", holds great significance in Tibetan Buddhism as it is believed to contain the essence of his teachings and embody his enlightened energy.

The first part of the mantra, "Om Ah Hum", represents the three aspects of the enlightened mind - body, speech, and mind. These three syllables also symbolize the three main deities in Tibetan Buddhism - Avalokiteshvara, Manjushri, and Vajrapani, who represent compassion, wisdom, and power.

The next part, "Vajra Guru", refers to Padmasambhava himself as the "Vajra Guru" or the "Diamond Master". This indicates his enlightened and indestructible nature, as the vajra is known for its strength and durability. Guru, on the other hand, signifies his role as a spiritual teacher and guide.

The third part, "Padma", means lotus and is a symbol of purity and spiritual growth. Padmasambhava is often depicted sitting on a lotus, representing his transcendence over worldly attachments and his attainment of enlightenment.

The fourth part, "Siddhi", means accomplishment or attainment. This refers to Padmasambhava's mastery over the spiritual path and his ability to guide others towards enlightenment.

The final part, "Hum", is a powerful seed syllable that represents the enlightened mind and the ultimate nature of reality. It is believed that by reciting this syllable, one can purify negative karma and achieve spiritual transformation.

Overall, this mantra encapsulates the essence of Padmasambhava's teachings - the union of compassion, wisdom, and power, and the path towards spiritual awakening and enlightenment. It is also believed to invoke his blessings and protection, making it a powerful tool for spiritual practice and transformation.

In addition to its spiritual significance, the mantra is also considered to have healing and transformative powers. It is often chanted or recited during rituals, meditations, and other spiritual practices to invoke Padmasambhava's presence and blessings.

In conclusion, Padmasambhava's famous mantra, "Om Ah Hum Vajra Guru Padma Siddhi Hum", is a powerful and sacred invocation that embodies the essence of his teachings and serves as a guide towards spiritual awakening and enlightenment. Its recitation is believed to bring about spiritual transformation, blessings, and protection, making it an integral part of Tibetan Buddhist practice.