Yahya related to me from Malik from Abu'z Zinad from al-Araj fromAbu Hurayra that the Messenger of Allah, may Allah bless him and granthim peace, said, "By the One in Whose hand my self is, the smell ofthe breath of a man fasting is better with Allah than the scent ofmusk.' He leaves his desires and his food and drink for My sake.Fasting is for Me and I reward it. Every good action is rewarded byten times its kind, up to seven hundred times, except fasting, whichis for Me, and I reward it.' "
USC-MSA web (English) reference: Book 18, Hadith 58
Arabic reference: Book 18, Hadith 691