Abu Hurairah reported,
The Messenger of Allah ﷺ said, "Every deed of the son of Adam is for him, except fasting. It is for Me, and I shall reward it. Fasting is a shield. When it is the day on which one of you fasts, let him not speak obscenely that day, nor raise his voice in clamor. If someone insults him or seeks to fight him, let him say, 'I am a man who is fasting,' twice.By the One in whose hand is the soul of Muhammad, the smell of the fasting person's mouth is more pleasing to Allah on the Day of Resurrection than the fragrance of musk. The fasting person has two joys in which he rejoices. When he breaks his fast, he rejoices at his breaking of the fast, and when he meets his Lord 
, he rejoices at his fasting."
Ahmad 7693
Sahihحدثنا عبد الرزاق وابن بكر قالا أخبرنا ابن جريج أخبرني عطاء عن أبي صالح الزيات أنه
سمع أبا هريرة يقول
قال رسول الله ﷺ كل عمل ابن آدم له إلا الصيام فإنه لي وأنا أجزي به والصيام جنة وإذا كان يوم صوم أحدكم فلا يرفث يومئذ ولا يصخب فإن شاتمه أحد أو قاتله فليقل إني امرؤ صائم مرتين والذي نفس محمد بيده لخلوف فم الصائم أطيب عند الله يوم القيامة من ريح المسك وللصائم فرحتان يفرحهما إذا أفطر فرح بفطره وإذا لقي ربه عز وجل فرح بصيامه
Its isnad is sahih. Abu Salih Zayyat is Abu Salih Samman, the father of Suhayl bin Abu Salih, whose name was Zakwan. He is called Zayyat, and he is also called Samman. His biography has already been given at 4626. We add here that Ibn Abu Hatim gave his biography at 1/2/450-451.The hadith was narrated by Muslim, 1:316, from Muhammad bin Rafi, from Abdul-Razzaq, from Ibn Jurayj, with this isnad. It makes explicit that its beginning is a hadith qudsi, in which Allah, mighty and exalted, said, "Every deed of the son of Adam belongs to him..." and so on to the end. Its meaning has already appeared, at length and in brief, and scattered across several hadiths, through various routes from Abu Hurairah, at 7174, 7194, 7484, 7485, and 7596, and we have documented many of its transmission paths in their respective places.