What specifically caused Kaka Mahajani's skeptical friend to forget his promise not to bow to Sai Baba?

The friend's change of heart was triggered by an auditory experience that was deeply personal and unexpected. According to Chapter 35, when the friend, who had resolved not to bow, set foot in the mosque, Sai Baba spoke to him. The text highlights that the friend was astonished because the "charming tone of the voice" was a "perfect imitation of his father's exact vocal style." Hearing speech as if from his deceased father's mouth caused the friend to melt inside. This powerful, emotional connection completely overrode his intellectual skepticism and prior resolve, leading him to bow at Baba's feet.