Musnad Ahmad 31:1

Hushaym narrated to us, Abu Bishr narrated to us, from Abu al-Mutawakkil, from Abu Sa’id al-Khudri, that some people from the companions of the Messenger of Allah (peace and blessings of Allah be upon him) were on a journey. They passed by a tribe of the Arab tribes and asked them for hospitality, but they refused to host them. Then, a person among them was afflicted in his mind—or stung. They said to the companions of the Messenger of Allah (peace and blessings of Allah be upon him): "Is there among you a raqi (one who performs ruqyah)?" A man among them said: "Yes." He came to their companion and performed ruqyah upon him with the Opening of the Book (Al-Fatiha), and he recovered. He was given a herd of sheep, but he refused to accept it until he came to the Prophet (peace and blessings of Allah be upon him) and mentioned that to him. He said: "O Messenger of Allah, by the One who sent you with the truth, I did not perform ruqyah upon him except with the Opening of the Book." He (the Prophet) laughed and said: "What made you know that it is a ruqyah?" Then he said: "Take them, and assign a share for me with you."