Sayyiduna Sahl bin Hunayf (may Allah be pleased with him) says: We passed by a flowing stream, so I went down into it and bathed, and when I came out I had a fever. This reached the Messenger of Allah (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Tell Abu Thabit to seek refuge with Allah (recite a ruqyah)." I said to him (peace and blessings be upon him): O my master! Is ruqyah permissible? He (peace and blessings be upon him) said: "No, except for three things: the evil eye, fever, and a sting (venomous bite)."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5594