(30) باب فَضْلِ الصِّيَامِ
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
Allah, the Majestic and the Exalted, said: Every act of the son of Adam is for him except fasting. It is done for My sake, and I will give a reward for it. By Allah in Whose Hand is the life of Muhammad, the breath of the observer of fast is sweeter to Allah than the fragrance of musk.
Reference: Sahih Muslim 1151 b
In-book reference: Book 13, Hadith 210
USC-MSA web (English) reference(deprecated numbering scheme): Book 6, Hadith 2564