Sahih Muslim Book 26, Hadith Number 5460.

Abu Sa’id al-Khudri reported. We landed at a place where a woman came to us and said: A scorpion has bitten the chief of the tribe. Is there any incantation amongst you? A person amongst us stood up (and went with her). We had no idea that he had been a good incantation but he practised incantation with the help of Sura al -Fatiha and the (the chief) was all right. They gave him a flock of sheep and served us milk. We said (to him): Are you a good incantator? Thereupon he said: I did not do it but by the help of Sura al-Fitiha. He said: Do not drive (these goats) until we go to Allah’s Messenger (may peace be upon him) and find out (whether it is permissible to accept (this reward of incantation). So we came to Allah’s Apostle (may peace be upon him) and made a mention of that to him, whereupon he said: How did you come to know that this (Sura al-Fatiha) could be used as an incantation? So distribute them (amongst those who had been present there with him) and allocate a share of mine also.