Times of the Prayers

Bukhari :: Book 1 :: Volume 10 :: Hadith 531

Narrated Abu Huraira:

Allah's Apostle said, "If anyone of you can get one Rak'a of the 'Asr prayer before sunset, he should complete his prayer. If any of you can get one Rak'a of the Fajr prayer before sunrise, he should complete his prayer."