How did Sai Baba prove to Cholkar that He was aware of his secret vow involving sugar?

The story of Cholkar illustrates Sai Baba's omniscience through a simple yet profound gesture. As detailed in Chapter 15, Cholkar had taken a private vow to abstain from sugar until he could visit Shirdi, a sacrifice he maintained even by drinking his tea without it. After Cholkar finally reached Shirdi and fulfilled his vow by distributing sugar, he was a guest of Mr. Jog. At this point, Sai Baba specifically instructed Jog, "Give him cups of tea, well-filled with sugar." Since Baba did not drink tea Himself, this unexpected command was a clear sign to Cholkar that Baba knew the secret details of his vow and the long period of his penance, causing tears of joy to stream from Cholkar's eyes.