In the story of the nephew with the bone-cyst, what was Sai Baba's specific instruction regarding the use of Udi?

In Chapter 34, after the suffering boy's parents pleaded with Sai Baba for help, he reassured them with compassion. The text states that Sai, the "embodiment of compassion," told them to remain worry-free. His direct instruction was a simple yet profound remedy for an ailment that baffled medical experts. He told them, "Take this Udi and smear it on that wound." This demonstrates how Udi was presented as the ultimate solution after all other medical and spiritual efforts had been exhausted, highlighting its divine healing power.