What exactly was Cholkar's promise to Sai Baba and what personal sacrifice did he make when he couldn't fulfill it right away?

Cholkar's promise to Sai Baba, as narrated in Chapter 15, was born out of desperation for his livelihood. For his job salary to become permanent, he needed to pass an examination. He made a 'firm resolve' that if he passed by Baba's grace, he would present himself at Baba's feet in Shirdi and distribute sugar candy, known as khadisakhar. After he passed, he was unable to fulfill this vow immediately due to financial hardship. As a personal sacrifice during this waiting period, Cholkar completely gave up sugar. The text notes that he avoided it 'as an inedible substance' and even drank his tea without sugar. This secret penance continued until he finally gathered the means to go to Shirdi and complete the offering he had promised.