How did Sai Baba demonstrate his omniscience to Cholkar during his visit to Shirdi?

Sai Baba demonstrated his omniscience in a deeply personal and astonishing way. After Cholkar fulfilled his vow by distributing sugar candy, he went to stay with Jog. As they were together, Baba called out to Jog and specifically instructed him to give Cholkar "cups of tea, well-filled with sugar." As Chapter 15 recounts, this statement astounded Cholkar because Baba did not drink tea, and more importantly, it directly referenced the very substance—sugar—that had been central to both his vow and his secret, personal penance of abstaining from it. This act proved to Cholkar that Baba was fully aware of his secret vow, the long delay, and the private sacrifice he had made, confirming Baba's all-knowing nature.