Can you explain the significance of faith in relation to Udi, using an example where the actual Udi wasn't even present?

The power of Sai Baba's Udi is immense, but its effectiveness is deeply connected to the devotee's faith. A remarkable story in Chapter 33 perfectly illustrates this principle. When a friend of Narayanrao was stung by a scorpion and suffering severe pain, they could not find any of Baba's Udi. In desperation, Narayanrao prayed before Baba's picture and took a pinch of ash from burnt incense sticks that had fallen near the frame. Considering this ash as Udi with complete faith, he applied it to the sting while chanting Sai's name. Miraculously, the pain subsided immediately, demonstrating that the true power lies not in the substance itself, but in the unwavering faith and belief in Sai Baba's grace.