Musnad Ahmad 31:84

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Ja'far ibn Iyas, from Abu Nadra, from Abu Sa'id al-Khudri, who said: The Messenger of Allah (peace and blessings of Allah be upon him) sent us in a military expedition of thirty riders. He said: We stopped by a people of the Arabs, and we asked them to host us, but they refused. He said: Then their leader was stung. He said: So they came to us and said: "Is there among you anyone who performs Ruqyah (incantation) for the scorpion sting?" He said: I said: "Yes, I am, but I will not do it until you give us something." They said: "We will give you thirty sheep." He said: So I recited 'Al-Hamd' (Surah Al-Fatiha) over him seven times. He said: So he recovered. He said: When we took possession of the sheep, something occurred in our minds regarding them. He said: So we refrained until we came to the Prophet (peace and blessings of Allah be upon him). He said: We mentioned that to him. He said: He replied: "Did you not know that it is a Ruqyah? Divide them and assign a share for me with you."