Sahih Muslim Book 6, Hadith Number 2568.

Chapter : Excellence of fasting.

Abu Huraira and Abu Sa’id (Allah be pleased with both of them) reported Allah’s Messenger (may peace be upon him) (as saying): Allah, the Exalted and Majestic, said: Fast (is exclusively) meant for Me and I would give its reward. There are two (occasions) of joy for the observer of fast. He feels joy when he breaks the fast and he is happy when he meets Allah. By Allah in Whose Hand is the life of Muhammad, the breath of the observer of fast is sweeter to Allah than the fragrance of musk. A Hadith like this is narrated on the authority of Abu Sinan with the same chain of transmitters (and the words are): “As he meets Allah, He rewards him, and he is happy.”