How did Sai Baba prove his omniscience to Cholkar through a simple cup of tea?

Sai Baba's omniscience was revealed to Cholkar in a deeply personal and astonishing way. As detailed in Chapter 15, after Cholkar had made a vow involving sugar candy, he was delayed in his pilgrimage to Shirdi. During this delay, he secretly gave up consuming sugar as a form of penance. When he finally arrived in Shirdi and fulfilled his vow, he was a guest at Jog's place. At that moment, Baba instructed Jog, "Give him cups of tea, well-filled with sugar." Since Baba himself did not drink tea, and Cholkar's sugar abstention was a secret, this specific command made Cholkar realize that Baba knew everything, including the secret state of his mind and the penance he undertook. This meaningful act brought tears of joy to Cholkar's eyes and immovably confirmed his faith.