Why did Appasaheb feel indebted to Sai Baba, and what promise did he make?

Appasaheb's feeling of indebtedness stemmed from a promise he made regarding a donation. As described in Chapter 33, his family had given only one Rupee to the Fakir, which Appasaheb felt was insufficient. He declared that had he been present, he would have given ten Rupees. Having made this verbal promise, he felt he could not be "debt-free" until he fulfilled his word completely. The text poses the question of how his word could be fulfilled and his debt cleared if he did not follow through on giving the ten Rupees he had pledged in his mind.