Sahih Muslim Book 4, Hadith Number 1066.

Chapter : Prayer in a single garment.

Abu Huraira reported: The Messenger of Allah (may peace be upon him) said: I have been helped by terror (in the heart of the enemy); I have been given words which are concise but comprehensive in meaning; and while I was asleep I was brought the keys of the treasures of the earth which were placed in my hand.