Mustadrak al-Hakim — Hadith 2078

Kharijah bin al-Salt al-Tamimi narrates from his paternal uncle that he passed by a people who had with them a madman bound in iron chains. One of them said to him: "Do you have anything with which he can be treated? For your companion (the Prophet, peace and blessings be upon him) has brought good." He said: I recited the Opening of the Book (al-Fatihah) over him for three days, twice every day, and he recovered. That man gave him a hundred sheep. He came to the Prophet (peace and blessings be upon him) and related the whole incident, and he (peace and blessings be upon him) said: "Eat, for whoever eats by means of a false ruqyah (is a sinner), but you have eaten by means of a true ruqyah."
The chain of this hadith is sahih (authentic), but the two Shaykhs (Bukhari and Muslim) did not record it.