How did Sai Baba demonstrate his omniscience to Cholkar regarding the renunciation of sugar?

Sai Baba demonstrated his all-knowing nature in a very personal and profound way for Cholkar. After Cholkar had made and delayed fulfilling his vow, he privately gave up sugar, even in his tea. When he finally came to Shirdi and was a guest of Jog, Baba said something remarkable. As noted in Chapter 15, just as Cholkar was about to leave, Baba told Jog, 'Give him cups of tea, well-filled with sugar.' These words astonished Cholkar, bringing tears to his eyes, because it was a clear sign that Baba knew the secret details of his vow, the long delay, and the personal penance he undertook. It was a 'full hint' that his devotion had been seen and accepted.