Why did Shama question Sai Baba about the offerings from the men from Goa, and what was Baba's explanation about debt?

According to Chapter 36, Madhavrao, also known as Shama, was perplexed by what he perceived as Sai Baba's partiality. He directly asked Baba why he would accept a fifteen-rupee Dakshina from one man but reject a larger, voluntarily offered sum of thirty-five rupees from his companion. Shama expressed that he would not act this way, finding it strange to show affection for a small amount of money but a selfless attitude toward a larger one. In response, Sai Baba began to explain a profound concept, stating, "Shama, you don't know; I don't take anything from anyone." He clarified that it is the 'Mother Masjid' that demands what is owed, allowing the giver to become free from their obligation. Baba concluded by stating that while he is detached from wealth, certain things like debt, enmity, and murder are inescapable and follow the doer.