Once, there was a renowned Sufi teacher who was extremely selective in choosing his students. He would ask his students to travel far and wide for his secret, and after so much traveling the students would always end up in some insignificant place with no secrets in their brains and souls. Sometimes he would ask them to run errands for him and even clean up the excretions his animals made. The students—including royal officials—tired themselves by mopping the floors of the shrine where he stayed, they tried their best to run every errand, which was in contradiction to their luxurious life and inherent Arab pride. But, no one could go on for long with the Sufi, and except for one person, people would give up after a certain period of time.
The Sufi never taught anything to the student who never gave up, but uttered these words to him in his last moments:
“The secret is to serve mankind unconditionally, and that would be enough for your ego to die.”