How exactly did Sai Baba prove his omniscience to Cholkar?

Sai Baba proved his omniscience to Cholkar through a deeply personal and specific action. According to Chapter 15, Cholkar had taken a private vow to distribute sugar if he passed an exam and had subsequently given up sugar himself while he saved money for the trip to Shirdi. This renunciation, including drinking his tea unsweetened, was a secret penance. After Cholkar finally arrived in Shirdi and fulfilled his vow, he was a guest at Jog's place. As he was leaving, Baba specifically told Jog, 'Give him cups of tea, well-filled with sugar.' This was astonishing because Baba did not drink tea himself, and the explicit instruction about sugar directly referenced Cholkar's secret sacrifice. This moment served as confirmation that Baba knew every detail of Cholkar's journey, from his initial vow to his private penance, thus proving his all-knowing nature.