What does the provided text say about Sai Baba's core teachings of shraddha and saburi?

The provided source material does not contain any information about Sai Baba's specific teachings on 'shraddha' and 'saburi.' Instead, the text from Chapter 0 focuses on the tradition and purpose of Guru biographies. It distinguishes between general spiritual knowledge texts and Guru biographies, explaining that the latter describe a Guru's life, miracles, and works. The chapter also details how studying these biographies can be a form of service, undertaken either with desire for worldly gains (Kamya) or selflessly for spiritual liberation (Nishkam), with Nishkam service being superior.