What exactly did Cholkar promise Sai Baba, and what personal sacrifice did he make while waiting to fulfill that promise?

According to Chapter 15, Cholkar's promise to Sai Baba was born out of desperation for job security. He made a "firm resolve" that if he were to pass a crucial examination, he would go to Shirdi and distribute sugar candy (khadisakhar) in Baba's name. After he passed, he faced a delay in making the journey. During this time, he undertook a specific personal penance: he completely gave up sugar. The text notes that until the vow to Shirdi was fulfilled, Cholkar "avoided sugar as an inedible substance, And even drank his tea without sugar." This act of renunciation was a secret he kept in his mind until Baba himself revealed knowledge of it.