How did Sai Baba demonstrate his omniscience to Cholkar after the vow was fulfilled?

After Cholkar finally traveled to Shirdi, had Sai's darshan, and fulfilled his vow by distributing sugar, he became a guest of Jog. As Chapter 15 recounts, Sai Baba then told Jog, "Give him cups of tea, well-filled with sugar." These words astonished Cholkar, bringing tears to his eyes. He knew Baba didn't drink tea and understood this as a direct acknowledgment of his secret, personal vow and the long period where he had given up sugar. Baba confirmed this was to strengthen Cholkar's faith, showing that even his most private acts of devotion were known to Him.