How did Sai Baba reveal his omniscience to Cholkar regarding the vow about sugar?

Sai Baba revealed his omniscience in a subtle yet powerful way after Cholkar had fulfilled his vow. As Cholkar was a guest at Jog's place, Baba specifically instructed Jog, "Give him cups of tea, well-filled with sugar." As noted in Chapter 15, this was remarkable because Baba himself did not drink tea. The instruction was a direct and meaningful sign to Cholkar, confirming that Baba was aware of both his original vow involving sugar and his secret, personal penance of abstaining from it during the delay. This miracle brought tears of joy to Cholkar's eyes, as it confirmed his faith.