Bhai Gurdas ji states that
ਵਾਹਿਗੁਰੂ ਗੁਰਮੰਤ੍ਰ ਹੈ ਜਪਿ ਹਉਮੈ ਖੋਈ।
His Guru-manta is Vahiguru, whose recitation erases egotism.
He says that the word “Vaheguru” is the Gurmantar. By doing Naam Japna (chant) or Naam Simran (remember) of this Gurmantar, you will lose your Haumai (ego). Haumai (ego) is the biggest illness inside us that keeps us separate from Vaheguru/Creator. The point of Sikhi is to get you away from the sense of separateness from the divine.