How did Sai Baba prove his omniscience to Cholkar and what was Cholkar's reaction?

Sai Baba proved his omniscience to Cholkar through a simple yet profound act detailed in Chapter 15. Cholkar had privately given up sugar as penance for delaying the fulfillment of a vow. When he finally arrived in Shirdi and was a guest of Jog, Baba told Jog to give Cholkar 'cups of tea, well-filled with sugar.' As these words fell on Cholkar's ears, he was completely amazed. He knew that Baba did not drink tea and that this instruction was meant solely for him. It was a secret confirmation that his vow and long penance were known to Baba. Overcome with emotion, tears of joy came to his eyes, and he placed his head at Baba's feet, his faith deeply confirmed.