Musannaf Ibn Abi Shaybah

Muhammad bin Sirin narrates that we were sitting with Abu Ubaidah in his dome when a man came to him and sat with him on his bed. He spoke secretly to Abu Ubaidah about something that we could not understand. Abu Ubaidah said to him, "Put your finger in this fire." There was a fire burning in a brazier among us. The man said, "Subhan Allah." So Abu Ubaidah said, "You are stingy with me about even a finger in the fire of this world, and you ask me to throw my whole body into the fire of Hell." The narrator says that we thought that the man had invited Abu Ubaidah to become a judge.