The Prophet ﷺ narrated from your Lord, who said, "Every deed has its expiation, but fasting is for Me, and I am the one who rewards it. The breath of the fasting person is more fragrant to Allah than the scent of musk."
عن النبي ﷺ يرويه عن ربكم قال: لكل عمل كفارة، والصوم لي، وأنا أجزي به، ولخلوف فم الصائم أطيب عند الله من ريح المسك.
Bukhari related it in the Book of Tawhid (7538), from Adam, from Shubah, "Muhammad bin Ziyad narrated to us, I heard Abu Hurairah say," followed by the account already mentioned. Muslim did not mention it in this wording.Ahmad related it (9888) from Muhammad bin Jafar, who is Ghundar, who said, "Shubah narrated to us," and it contains, "Every deed has its atonement, but fasting is for Me..."His saying, "For every deed" (meaning every sin) there is an "atonement" from acts of obedience. As for the meaning of Ghundar's hadith, it means every deed of obedience serves as atonement for sins.