What exactly is Udi, and how did Sai Baba give it to his followers?

Udi is the sacred ash taken from the Dhuni, the fire that burned constantly day and night in Baba's Masjid. As described in Chapter 33, Baba would give handfuls of this ash to devotees as a benediction, or Prasad. He would often apply it to their foreheads with his own thumb and place his hand on their heads, wishing for their welfare. The terms Udi, Vibhuti, and ash are all used to describe this blessed offering which Baba distributed daily and without limit to all who came to him.