Narrated Abu Huraira:
Allah’s Apostle said, “When Ramadan begins, the gates of Paradise are opened.”
(Bukhari :: Book 3 :: Volume 31 :: Hadith 122)
Abu Huraira related that the Prophet (peace be upon him) said: Allah the Majestic and Exalted said: “Every deed of man will receive ten to 700 times reward, except Siyam (fasting), for it is for Me and I shall reward it (as I like). There are two occasions of joy for one who fasts: one when he breaks the fast and the other when he will meet his Lord” (Muslim).