Sahih Adab al-Mufrad

It is narrated from Thumamah bin Hazn that he said: I heard a sheikh loudly saying: «اللهم إني أعوذ بك من الشر لا يخلطه شيء» "O Allah! I seek refuge with You from such evil in which there is nothing mixed (pure evil)." I asked, who is this sheikh? It was said: Abu Darda.