It is narrated from Sayyiduna Sahl bin Hunayf (may Allah be pleased with him) that he said: We passed by a stream of flood water, so I entered it and bathed in it, 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 (Sahl bin Hunayf) to recite ruqyah (seek refuge)." I said: O my master, is ruqyah beneficial? He (peace and blessings be upon him) said: "There is no ruqyah except for the evil eye, a venomous effect, or the sting of a (venomous creature)" (that is, it is most effective in these). This hadith has a sahih (authentic) chain of narration, but the two Shaykhs did not record it.