How did Sai Baba bless the devotee Gopalrao Gund, and what did Gund try to do for Baba in return?

The Introduction (Chapter 0) recounts how Sai Baba bestowed a significant blessing upon Gopalrao Gund, the Revenue Circle Inspector of Kopargaon. Despite having three wives, Gund was childless, and he received the blessing of a son from Maharaj. Filled with devotion, he became a total devotee. In gratitude, he wished to serve Baba by rebuilding the dilapidated Masjid where Baba lived. He went so far as to collect a large number of stones for the construction. However, Baba did not permit this, indicating the task was for someone else, and instead directed Gund to use the stones to build a Shani temple and renovate other village temples.