Can you tell me the story of Cholkar's vow to Sai Baba and how it was fulfilled?

Cholkar was a poor man who needed to pass an examination to secure his job. As described in Chapter 15, he made a vow to Sai Baba that if he passed, he would visit Shirdi and distribute sugar candy. After passing the exam, he faced financial difficulties which delayed his trip. To uphold his vow during this time, he gave up sugar completely, even drinking his tea without it. When he finally managed to visit Shirdi, he fulfilled his vow by distributing sugar. In a beautiful display of omniscience, Baba then specifically told Cholkar's host, Jog, to serve him tea that was "well-filled with sugar," proving to Cholkar that Baba knew all about his secret vow and personal sacrifice.