How did Sai Baba demonstrate his omniscience and correct his devotees' hidden actions?

Sai Baba's all-knowing nature is clearly described in Chapter 19. It states that if a devotee tried to practice Hatha Yoga in secret, Baba would know it through his omniscience and would correct them with a sharp "arrow (of words)." In another demonstration of this ability, he once sent a message through a complete stranger to a devotee, saying, "Why can't you sit still after eating your bread? Stay with patience." These examples from the source text show that Baba was aware of his followers' most secret actions and thoughts, and he would use this knowledge to guide them, sometimes directly and sometimes through mysterious means, ensuring they stayed on the right path.