"Every good deed of the son of Adam will be multiplied. He will receive ten-fold to seven-hundred-fold reward for a good deed. Allah the Glorious and Majestic has said 'but fasting is exceptional, for it is done for Me and I will give reward for it, since one abandons his passion and food for My sake. There are two occasions of joy for one who fasts, joy when he breaks it and joy when he meets his Lord; and the breath (of an observer of fast) is sweeter to Allah than the fragrance of musk."
[Related by AI-Bukhari and Muslim].