What was the specific role of Udi in granting devotees permission to leave Shirdi, as mentioned in Chapter 33?

As detailed in Chapter 33 of the Sai Satcharitra, the distribution of Udi played a crucial role when devotees sought permission to leave Shirdi. It was a well-known practice that when a devotee wished to return to their village, they would ask for Baba's leave. The true confirmation of this permission was given when Baba gave them the sacred Udi. The text states, 'when saying "Take the Udi," true permission was granted then.' This act was more than just a formality; it filled the departing devotee with enthusiasm and assurance, as they knew they were leaving with Baba's explicit blessing and protection, symbolized by the sacred ash they carried with them.