The Messenger of Allah ﷺ said, "Allah says, 'Fasting is for Me, and I Myself shall reward it.' The one who fasts has two moments of joy. He rejoices when he breaks his fast, and he rejoices when he meets Allah and is rewarded by Him. By the One in whose hand is the soul of Muhammad, the breath of the fasting person is more fragrant to Allah than the scent of musk."
حدثنا محمد بن فضيل حدثنا ضرار وهو أبو سنان عن أبي صالح
قال رسول الله ﷺ إن الله يقول إن الصوم لي وأنا أجزي به إن للصائم فرحتين إذا أفطر فرح وإذا لقي الله فجزاه فرح والذي نفس محمد بيده لخلوف فم الصائم أطيب عند الله من ريح المسك
Its chain of transmission is sahih. Darrar is Darrar bin Mura, Abu Sinan Shaybani the Elder, whose reliability and biography were already covered at 1557. The hadith is actually two hadiths, since it comes from the narration of two companions, Abu Hurairah and Abu Saeed. It will also come again in the Musnad of Abu Saeed, with this same chain, at 11022. Muslim narrated it, 1:217, through Muhammad bin Fudayl, and also through Abdul-Aziz bin Muslim, both of them from Abu Sinan, with this chain.Bukhari narrated it from the hadith of Abu Hurairah alone, 4:101, with a similar meaning, from the narration of Ataa from Abu Salih from Abu Hurairah. Muslim likewise narrated it, 1:316–317, from the narration of Ataa, and he also narrated it from the narration of Amash from Abu Salih from Abu Hurairah. Something with a similar meaning has already appeared at 4256, from the hadith of Abdullah bin Masud.Khuluf, with the kha pronounced with damma, means the changing of the smell of the mouth.