Describe the promise the Tarkhad son made his father agree to before he would leave for Shirdi.

The Tarkhad son was a devout worshipper of Sai and was concerned about who would perform the daily worship and Naivedya (food offering) in his absence. As detailed in Chapter 9, his father followed the Prarthana Samaj, which made the son hesitant to entrust him with idol worship. Therefore, before agreeing to travel, the son made his father promise that no one in the household would consume food without first offering Naivedya to Sai. The father gave his word, assuring his son he would perform the duty daily, which finally convinced the son to make the journey to Shirdi.