True King, which name is the most efficacious ?” The Guru, says Bhai Mani Singh, Sikhan di Bhagat Mala, replied, “Any boat would take one across a river, but one should stick to the boat one has boarded. All names of God lead to liberation. For Sikhs the name revealed by Guru Nanak is Vahiguru.” Bhai Changa and his companions concentrated on the name Vahiguru and told others to do so.
References :
1. Mani Singh, Bhai, Sikhan di Bhagat Main. Amritsar, 1955
2. Santokh Singh, Bhai, Sri Gur Pratap Suraj Granth. Amritsar, 1926-37