Can you describe the specific practice the Patil followed when performing his 'Satya-Sai vow' as detailed in Chapter 13?

Certainly. Chapter 13 provides specific details about the Patil's unique vow. He established the 'Satya-Sai vow' as a parallel to the traditional Satyanarayan vow. The ritual involved performing the vow on Thursdays after bathing. The central part of the practice was reading a specific text. Instead of the Satyanarayan story, the Patil would read the three chapters dedicated to Sainath from the book 'Bhaktalilamrut,' written by Das Ganu. This act of reading Sai's character and stories, accompanied by offerings and celebration, was the core of the vow. This new tradition, which equated Sai with Narayan, brought the Patil 'boundless happiness' and became a regular custom.