Musnad Ahmad 32:884

Sahl ibn Yusuf—meaning al-Masma‘i—narrated to us, from Humayd; and Yazid ibn Harun informed us, from Humayd, from Anas, who said: The Messenger of Allah (ﷺ) arrived in Medina, and the people of Medina had two days in which they would play. He said: "I have arrived among you, and you have two days in which you play. Indeed, Allah has replaced them for you with two days better than them: the day of al-Fitr and the day of al-Nahr."