Bayazid Bastami was a Persian Sufi from north-central Iran.Hazrat Bayazid Bastami once went to Deir Samaan, that day was the day of Christian Eid. Monks from different areas were coming to listen to the speech of the great monk of Deir Simaan.
When the big monk came and sat on the stage and could not deliver his speech, then he said, "There is a Mohammedan (Muslim)among you." Everyone said, "Show us that person, we will kill him immediately." He said, "Don't kill him without argument and evidence. I will ask him a few questions as a test." If he answers all the questions correctly, we will release him, otherwise, we will kill him.
That Chief Christian monk stood on the stage and started calling, O Mohammedan! By the oath of Muhammad (PBUH), stand up so that everyone can see you, then Hazrat Bayazid Bastami stood up.
This great priest said, O Mohammedan, I ask you a few questions. If you answered all these questions clearly, then we will follow you, otherwise, we will kill you. Hazrat Bayazid Bastami answered all their questions and those people became Muslims knowing the truth of Islam.