Hazrat Abu Zubyan narrates that Hazrat Usama said: The Messenger of Allah, peace and blessings be upon him, sent us with an army. We reached the gardens of the tribe of Juhaina in the morning, and I encountered a man who said: "There is no god but Allah." But I struck him with a spear. After that, I felt uneasy about this in my heart. I mentioned this to the Prophet, peace and blessings be upon him, and the Messenger of Allah, peace and blessings be upon him, said: "He said 'There is no god but Allah,' and yet you killed him?" I said: "O Messenger of Allah, peace and blessings be upon him! He only said this out of fear of the weapon!" He, peace and blessings be upon him, said: "Why did you not cut open his heart so you would know whether he said it out of fear or not?" He (Usama) says: The Prophet, peace and blessings be upon him, kept repeating this to me until I wished that I had only accepted Islam that very day.