The Messenger of Allah ﷺ said, "Fasting is for Me, and I Myself shall reward it. The one who fasts experiences two moments of joy, when he breaks his fast and on the day he meets Allah. The breath of the one fasting is more fragrant to Allah than the scent of musk."
أخبرنا سليمان بن داود عن ابن وهب قال أخبرني عمرو أن المنذر بن عبيد حدثه عن أبي صالح السمان
عن رسول الله ﷺ قال الصيام لي وأنا أجزي به والصائم يفرح مرتين عند فطره ويوم يلقى الله وخلوف فم الصائم أطيب عند الله من ريح المسك
[Sahih] It is found in Sunan al-Kubra, hadith no. 2524. Amr is Ibn Harith, and the hadith has many paths of transmission. See the previous and following hadith.