Can you tell me about Sai Baba's time with his Guru? What was their relationship like?

In Chapter 19, Sai Baba recounts his deep and loving relationship with his Guru, whom he describes as a "great Auliya" and an "ocean of mercy." For twelve years, Baba served him tirelessly, wearing himself out in service with the strong desire to receive a mantra. During this time, the Guru provided for all his needs, and Baba felt immense love, stating his Guru was a "veritable idol of devotion and love." Baba's devotion was so all-consuming that he would gaze at his Guru's face day and night, feeling neither hunger nor thirst, and his mind was restless without him. This constant contemplation was all the Guru expected, and in return, he always protected Baba.