Can you explain the significance of Udi and how faith plays a role, using examples from Chapter 33?

Chapter 33 describes Udi as "supremely auspicious" and a medium through which Sai Baba grants both spiritual welfare and fulfills worldly needs. Its power is deeply intertwined with the devotee's faith. For example, when Narayanrao's friend was stung by a scorpion, they used simple ash from an incense stick, but with the belief that it was Udi. This act of faith, combined with chanting Sai's name, instantly relieved the pain. A footnote also mentions a Jyotishi Buwa who was cured of a scorpion sting's severe pain after applying Udi and continuously doing Nama Smarana, which established his faith. These stories show that the efficacy of Udi is magnified by unwavering belief in Baba.