What specific sacrifice did Cholkar undertake while waiting to fulfill his vow, and how did Sai Baba acknowledge it?

According to Chapter 15, after Cholkar's wish to pass his examination was granted, he faced a delay in visiting Shirdi to fulfill his vow. To maintain his resolve, he gave up sugar entirely, viewing it as an "inedible substance" and even drinking his tea without it. Sai Baba acknowledged this secret penance in a remarkable way. When Cholkar was visiting, Baba instructed a devotee named Jog to "Give him cups of tea, well-filled with sugar." This specific instruction, coming from Baba who did not drink tea himself, was a clear and powerful sign to Cholkar that his private sacrifice was known and his vow was accepted.