How did Sai Baba produce the Udi he distributed, and what specific role did it play when devotees were preparing to leave Shirdi?

As detailed in Chapter 33 of the Sai Satcharitra, Sai Baba produced the sacred Udi through his Dhuni, or sacred fire, which was kept constantly burning in the Masjid. The process involved him buying bundles of firewood, sometimes using money collected as Dakshina, and offering these dry logs into the fire. The ash that remained was the Udi he would give to devotees. The chapter clarifies the specific role of Udi for those departing. When devotees asked for permission to leave Shirdi and return to their villages, Baba would give them Udi. This act of giving the ash was known to all devotees as the true granting of permission, which would in turn make the departing devotee feel enthusiastic.