Can you describe the 'Satya-Sai vow' mentioned in Chapter 13 and how it started?

According to Chapter 13, the 'Satya-Sai vow' was a tradition started by a grateful Patil who was cured of a disease by Sai Baba's grace. This practice was inspired by the common custom of vowing to perform a Satyanarayan puja to overcome a crisis. The Patil adapted this for his devotion to Sai. Every Thursday, after bathing, he would observe the vow. Instead of reading the traditional Satyanarayan story, the Patil would read the three chapters dedicated to Sainath from the modern Bhaktalilamrut written by Das Ganu. The text notes that he would perform this vow regularly with offerings and celebrations, finding 'boundless happiness.' This practice, which equates Sai with Narayan, became a popular custom in his village.