Musnad Ahmad 1153:1516

Waki’ narrated to us, from Hisham ibn ‘Urwah, from his father, from ‘Aishah, who said: The Abyssinians were playing on a day of Eid, so the Messenger of Allah (peace and blessings of Allah be upon him) called me, and I was looking over his shoulder, watching them. Then Abu Bakr came, and the Prophet (peace and blessings of Allah be upon him) said: "Leave her, for every people have an Eid, and this is our Eid."