What vow did Cholkar make to Sai Baba, and what personal sacrifice did he undertake when he couldn't immediately fulfill it?

Cholkar, facing an important examination to make his job permanent, made a vow to Sai Baba. As described in chapter 15, he resolved that if he passed the exam by Baba's grace, he would visit Shirdi and distribute sugar candy (khadisakhar) in Baba's name. After his wish was granted and he passed, he faced financial difficulties that delayed his journey. As a personal penance for this delay, Cholkar gave up sugar entirely, going so far as to drink his tea without it until he could finally fulfill his vow in Shirdi.