How did Sai Baba demonstrate his omniscience regarding Cholkar's secret vow and personal sacrifice?

Sai Baba revealed his knowledge of Cholkar's situation in a subtle yet powerful manner. After Cholkar had finally arrived in Shirdi, fulfilled his vow by distributing sugar, and was visiting his host, Jog, Baba made a specific request. As detailed in Chapter 15, Baba told Jog, "Give him cups of tea, well-filled with sugar." This instruction was profound because Baba himself did not drink tea, and more importantly, he knew Cholkar had been abstaining from sugar for a long time. Hearing these words, Cholkar was amazed and moved to tears, as it was undeniable proof that Baba was aware of his secret vow, the delay, and his personal penance.