What does the preface to the Sai Satcharita say about the teachings of Saint Tukaram?

The provided preface from the Shri Sai Satcharita does not contain any specific information or mention of the teachings of Saint Tukaram. However, the author does reference another great saint, Dnyaneshwar Maharaj. In Chapter 0, the preface quotes from Shri Dnyaneshwari, the commentary on the Bhagavad Gita by Dnyaneshwar Maharaj, to emphasize the importance of serving saints with one's entire being to gain true knowledge and dispel doubts. This highlights the broader principle of Guru service that is central to the preface.