What was the specific vow Cholkar made, and how did Sai Baba show him it was accepted?

As recounted in Chapter 15, Cholkar made a firm resolve that if he passed an essential examination for his job, he would present himself at Sai Baba's feet and distribute sugar candy (khadisakhar) in Baba's name. After passing, he was delayed in fulfilling this vow. When he finally arrived in Shirdi, he distributed the sugar as promised. The ultimate confirmation that his vow was accepted came in a miraculous way. After the formalities, Baba told Cholkar's host, Jog, to serve him cups of tea that were 'well-filled with sugar.' This was a meaningful sign for Cholkar, who had secretly given up sugar during the delay, proving that Baba knew the intimate details of his devotion and penance, confirming his faith was recognized.