The people doubted whether the Prophet (ﷺ) was fasting on the day of `Arafat or not, so I sent milk while he was standing at `Arafat, he drank it and the people were looking at him.
Sahih al-Bukhari Book 30, Hadith 96
← Previous Hadith "While the people were with me on the day of `Arafat they differed as to whether the Prophet (ﷺ) was fasting or not; some said that he was fasting while others said that he was not fasting. So, I sent to him a bowl full of milk while he was riding over his camel and he drank it."

Sahih al-Bukhari Book 30, Hadith 95 Next Hadith → (the slave of Ibn Azhar) I witnessed the `Id with `Umar bin Al-Khattab who said, Allah's Messenger (ﷺ) has forbidden people to fast on the day on which you break fasting (the fasts of Ramadan) and the day on which you eat the meat of your sacrifices (the first day of `Id ul Fitr and `Id ul-Adha).

Sahih al-Bukhari Book 30, Hadith 97