What was the promise Babasaheb Tarkhad made to his son before his son would agree to go to Shirdi?

According to the story in Chapter 9, Babasaheb Tarkhad's son was a devout follower of Sai who would not eat without first offering Naivedya to a photograph of Sai. When his mother wished to go to Shirdi, the son was hesitant to leave, worried that this daily worship would be interrupted. To convince him, Babasaheb promised that he would personally continue the tradition. He gave his word that 'Without offering Naivedya to Sai, no one should consume food at home.' Only after receiving this firm assurance did the son agree to make the journey to Shirdi.