Musnad Ahmad 33:1118

Hassan narrated to us, Ibn Lahi'ah narrated to us, Abu al-Zubayr narrated to us, from Jabir, that 'Amr ibn Hazm was called for a woman in Medina who had been stung by a snake, in order for him to perform ruqyah (incantation) upon her, but he refused. That was reported to the Messenger of Allah, peace and blessings of Allah be upon him, so he called him. 'Amr said: "O Messenger of Allah, you forbid ruqyah." He said: "Recite it to me." So he recited it to him. The Messenger of Allah, peace and blessings of Allah be upon him, said: "There is no harm in it; it is only covenants by which one seeks relief."