Why did Sai Baba instruct Amir Shakkar, who was suffering from rheumatism, to stay in the dilapidated Chavadi?

Chapter 22 explains that when Amir Shakkar, afflicted by rheumatism, prayed to Sai Baba for a remedy, Baba's instruction was for him to stay in the Chavadi. Although the Chavadi was old, dilapidated, and in terrible condition, Baba's words were firm. He told Amir not to weigh the external conditions like wind, rain, or dampness. This directive served as a test of faith. By accepting Baba's word as the ultimate medicine and enduring the harsh physical environment, Amir's internal faith was strengthened, and he was rewarded with the constant company of Sai, which was considered the 'Great Prasad'.