How did Sai Baba use a request for Dakshina to remind a devotee of a forgotten promise?

Chapter 36 recounts the story of a man who, seeking a job to support his family, made a vow to Lord Datta. He promised to offer his entire first month's salary if his prayer was answered. He soon found a job with a salary of fifteen rupees and later received promotions, but he completely forgot his vow. When this man visited Sai Baba, Baba's request for money was not a form of begging for Dakshina; rather, as the text explains, it was a pretext to remind the devotee of the repayment of this old, forgotten debt.