Why did Cholkar give up sugar, and how did Sai Baba show that he knew about this secret penance?

Cholkar gave up sugar as a personal penance because he was delayed in fulfilling his vow to Sai Baba. As described in Chapter 15, after passing his exam, Cholkar faced financial difficulties that prevented him from traveling to Shirdi. Feeling troubled by this delay, he resolved to abstain from sugar, even drinking his tea without it, until he could complete his promised offering. Sai Baba revealed his knowledge of this secret sacrifice in a miraculous way. After Cholkar finally arrived in Shirdi and fulfilled his vow, Baba specifically instructed another devotee, Jog, to 'Give him cups of tea, well-filled with sugar.' This astonished Cholkar, proving that Baba was aware of his private act of devotion and the reason behind it, solidifying his faith.