The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 1067
Hammam b. Munabbih reported: That is what Abu Huraira reported to us from the Messenger of Allah (may peace be upon him) and he narrated (some) ahadith one of which is that the Messenger of Allah (may peace be upon him) said: I have been helped by terror (in the hearts of enemies) and I have been given words which are concise but comprehensive in meaning.