Sahih Bukhari Volume 1, Book 10, Hadith Number 568

Narated By Ibn Abu Malih : I was with Buraida on a cloudy day and he said, “Offer the ‘Asr prayer earlier as the Prophet said, ‘Whoever leaves the ‘Asr prayer will have all his (good) deeds annulled.” (See Hadith No. 527 and 528)