Abu Dawud Book 7, Hadith Number 2358.
Chapter : Not known.
Narated By A Companion of the Prophet : AbuBakr ibn AbdurRahman reported on the authority of a Companion of the Prophet (PBUH): I saw the Prophet (PBUH) commanding the people while he was travelling on the occasion of the conquest of Mecca not to observe fast. He said: Be strong for your enemy. The Apostle of Allah (PBUH) fasted himself.