Sahih Muslim | Book 35 | Hadith Number 6552

Narrated by Abu Huraira
Abu Huraira reported that Allah's Messenger (may peace be upon him) used to command us that as we go to our bedo, we should utter the words (as mentioned above) and he also said (these words): "From the evil of every animal, Thou hast hold upon its forelock (Thou hast full control over it).