Musnad Ahmad 30:2784

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Dawud ibn Farahij, who said: I heard Abu Hurairah narrating from the Prophet, may Allah bless him and grant him peace, that he said: "Allah, the Mighty and Majestic, says: 'Fasting is for Me, and I reward for it.'" "And the change in the breath of the fasting person is more pleasant to Allah than the scent of musk."