Can you tell me about the vow Cholkar made to Sai Baba and why it was so important for him?

The story from Chapter 15 recounts that a man named Cholkar from a poor household was facing a critical examination. His job and daily bread depended on passing it. In his desperation, he made a vow to Sai Baba, promising that if he passed by Baba's grace, he would visit Shirdi and distribute sugar candy (khadisakhar) in His name. This was a firm resolve for Cholkar because, as the text states, his entire livelihood was at stake. After his wish was granted and he passed the exam, he faced another hurdle: the poverty that delayed him from immediately fulfilling his promise to travel to Shirdi.