How did Sai Baba prove to Cholkar that he knew about his secret promise to give up sugar?

Sai Baba demonstrated his omniscience to Cholkar in a subtle yet powerful way. After Cholkar had arrived in Shirdi and officially fulfilled his vow by distributing sugar, he was staying with a devotee named Jog. As Cholkar was about to leave Jog's place, Sai Baba, who notably did not drink tea himself, specifically told Jog, "Give him cups of tea, well-filled with sugar." As noted in Chapter 15, hearing these meaningful words astonished Cholkar. This direct reference to sugar, the very substance of his private and long-held vow, was undeniable proof that Baba was aware of his secret penance all along. This confirmation moved Cholkar to tears and solidified his faith.