Why did Cholkar stop eating sugar, and what was the vow he made to Sai Baba?

According to Chapter 15, Cholkar's livelihood depended on passing an examination to make his job permanent. He made a firm resolve, a vow to Sai Baba, stating that if he passed by Baba's grace, he would visit Shirdi and distribute sugar candy (khadisakhar). After his wish was granted, he was unable to travel to Shirdi immediately due to financial constraints, which the text poetically calls the "threshold-ghat." Because of this delay in fulfilling his promise, Cholkar decided to give up sugar as a form of penance and a constant reminder of his unfulfilled vow, even drinking his tea without it until he could finally make the journey.