In the story of Boss Dharamsee, why did Kaka bring grapes as an offering to Baba in the first place?

The narrative in Chapter 35 explains the motivation behind Kaka's offering. The text states a guiding principle that 'it is not good to go empty-handed to the door of God, a priest, or a Guru.' Adhering to this custom, Kaka purchased two seers of grapes while on his way to Shirdi to present to Sai Baba. Although he could not find the seedless variety he preferred, he bought the available ones with seeds. This act of bringing a humble offering was pivotal, as it became the very object through which Baba performed a miracle that transformed the skeptical Boss Dharamsee, demonstrating the importance of the devotee's gesture of giving.