It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: By Him in Whose hand is the soul of Muhammad (peace and blessings be upon him), the breath of the fasting person is more pleasant to Allah than the fragrance of musk.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7493
Hadith Gradingحکم دارالسلام:حديث صحيح، خ: 7492، م: 1151، محمد بن إسحاق- وإن رواه بالعنعنة وهو مدلس- قد توبع.