The Messenger of Allah ﷺ said: “Allah — Mighty and Majestic is He — said: ‘Every action of the son of Adam is for himself, except for fasting, for it is for Me, and I will give the reward for it.’” (Bukhārī & Muslim)
قال رسول الله صلى الله عليه وسلم: قال الله عز وجل: كل عمل ابن آدم له إلا الصيام، فإنه لي، وأنا أجزي به. متفق عليه