What is the significance of Udi as described in Chapter 34, and what was Sai Baba's specific instruction for its use in the boy's case?

Chapter 34 of the Shri Sai Satcharitra extols the glory and majesty of Udi, presenting it as a divine remedy with miraculous healing properties. The chapter continues the theme from the previous one, using the story of the doctor's nephew to illustrate that Udi can cure even incurable diseases like a bone-cyst. Its significance lies in it being a physical manifestation of Sai Baba's grace and power. When the boy's desperate parents came to Shirdi, Sai Baba reassured them completely. His specific instruction, as recorded in this chapter, was simple yet profound: "Take this Udi and smear it on that wound." This act of applying the sacred ash was the key to uprooting the ailment, showcasing that faith combined with the Guru's blessing in the form of Udi was the ultimate solution.