I attended the 'Id (prayer) along with 'Umar. He offered prayer before the sermon. He then said: The Messenger of Allah (ﷺ) prohibited fasting on these two days. As regards Id al-Adha, you eat the meat of your sacrificial animals. As for 'Id al-Fitr, you break (i.e. end) your fast.
Sunan Abi Dawud Book 14, Hadith 104
← Previous Hadith The Prophet (ﷺ) said: One of you should not say: I fasted the whole of Ramadan, and I prayed during the night in the whole of Ramadan. I do not know whether he disliked the purification; or he (the narrator) said: He must have slept a little and taken rest.

Sunan Abi Dawud Book 14, Hadith 103 Next Hadith → The Messenger of Allah (ﷺ) forbade fasting on two days, al-Fitr (breaking the fast of Ramadan) and al-Adha (the day of sacrifice), and wearing a tight single garment the raising of which discloses private parts, and sitting with one's legs drawn up and wrapped in one's garment, and forbade praying at two hours, after the Fajr prayer and after the Asr prayer.

Sunan Abi Dawud Book 14, Hadith 105