He was very surprised. He prayed and asked God, “What is the matter? What are you trying to reveal to me?” And it is said that he heard a voice. God said, “There are three types of people: one, who hear through one ear; it never reaches anywhere — in fact they don’t hear, just the sound vibrates and disappears. There is another type, who hear, but only momentarily — they hear through one ear, and through the other ear it is lost into the world again. There are a few souls, of course, who hear through the ears and it reaches to the heart.”
And God said, "Bayazid, I have brought you to this heap of skulls just to help you remember it when you are talking to people. Talk only to those who take whatsoever you say to their hearts — otherwise don’t waste your energy, and don’t waste your time. Your life is precious: you have a message to deliver."