How is one supposed to use Udi for protection, for example, against bad dreams or other troubles?

Chapter 35 provides a specific method for using Udi as a remedy for spiritual or mental disturbances. In the story of a gentleman from Bandra troubled by nightmares, a Sai devotee advised him on the proper application. The instructions were to apply a small amount of the sacred ash to the forehead when going to sleep. Additionally, he was told to tie a packet of Udi and keep it under his pillow. Crucially, this physical application was to be accompanied by mental devotion, specifically by remembering Shri Sai in one's mind and keeping faith in the heart. The text suggests that when used with this combination of physical application and heartfelt devotion, the Udi's "natural tendency" to remove trouble is immediately effective.