Can you explain the origin and practice of the 'Satya-Sai vow' as described in the provided text?

The 'Satya-Sai vow' was a tradition started by the Patil out of gratitude for Sai Baba's grace. As explained in Chapter 13, this practice was modeled after the Satyanarayan vow, which people performed to overcome crises. The Patil adapted it to honor Sai. On Thursdays, after bathing, he would read the three chapters about Sainath from the 'modern Bhaktalilamrut' written by Das Ganu, considering them the 'Satya-Sai story.' The Patil performed this vow regularly with offerings and celebrations, seeing no difference between Narayan and Sai. This practice, which brought him boundless happiness, became a custom in his village.