Abu Dawud Book 2, Hadith Number 426.
Chapter : Not known.
Narated By Umm Farwah : The Apostle of Allah (PBUH) was asked: Which of the actions is best? He replied: Observing prayer early in its period.
Al-Khuza’i narrated in his version from his aunt named Umm Farwah who took the oath of allegiance to the Prophet (PBUH): He was questioned.