Sayyiduna Jabalah bin al-Azraq (may Allah be pleased with him), who was one of the Companions of the Messenger of Allah (peace and blessings be upon him), relates that the Messenger of Allah (peace and blessings be upon him) prayed beside a wall that had many holes in it. He prayed Zuhr or Asr, and when he sat after the two rak'ahs, a scorpion came out and stung him, and he fainted. The people recited ruqyah over him, and when he regained consciousness he said: "Allah has cured me, not your ruqyah."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2183