Why did Sai Baba keep a sacred fire, the Dhuni, constantly burning, and what did he do with the logs and the resulting ash as described in Chapter 33?

Chapter 33 describes Sai Baba's process with the sacred fire, or Dhuni. He would buy bundles of firewood from those who had a surplus and pile them up. He then offered these dry logs into the Dhuni, which he kept constantly burning in the Masjid. The primary purpose of this constant fire was to produce a great quantity of sacred ash, known as Udi. This Udi was central to his teachings and interactions with devotees. As the chapter narrates, he would apply this Udi to devotees and distribute it as a blessing and a profound lesson on the impermanence of the material world.