What is the story of Das Ganu and the holy bath at Prayag as told in Chapter 22?

According to the account in Chapter 22, the devotee Das Ganu sought permission from Sai Baba to go on a pilgrimage to bathe in the holy waters at Prayag. In response, Baba told him that the journey was unnecessary. Baba proclaimed, "Know this big toe of Mine to be Prayag; bathe right here." When Das Ganu accepted this and placed his head on Baba's feet in reverence, a miracle occurred. As the chapter recounts, the waters of both the Ganga and Yamuna rivers manifested right there from Baba's big toe, satisfying Das Ganu's desire and demonstrating that the Guru's feet are the ultimate holy site.