Musnad Ahmad 5:6

Abu Sa’id narrated to us, Sa’id ibn Salamah ibn Abi al-Husam—a Medinan, a freed slave of the family of ‘Umar—narrated to us, Yazid ibn ‘Abd Allah ibn al-Had narrated to us, from ‘Amr ibn Sulaym, from his mother, who said: While we were in Mina, ‘Ali ibn Abi Talib, may Allah be pleased with him, was saying: "Indeed, the Messenger of Allah, peace and blessings of Allah be upon him, said: 'These are days of eating and drinking, so let no one fast them.'" And he followed the people on his camel, shouting that.