How did Sai Baba demonstrate his omniscience regarding Cholkar's secret vow and personal renunciation of sugar?

When Cholkar finally made it to Shirdi and fulfilled his vow, he had a profound experience that confirmed Baba's omniscience. As detailed in Chapter 15, after Cholkar had darshan and was visiting with a man named Jog, Sai Baba gave a specific instruction. He told Jog, "Give him cups of tea, well-filled with sugar." These words amazed Cholkar, as Baba did not drink tea himself, and it directly addressed the very substance of his vow and the secret penance he had undertaken. This act showed Cholkar that Baba knew everything, including his vow, the long delay, and his private act of giving up sugar.