Narrated Aisha, Ummul Mu'minin: The Messenger of Allah (ﷺ) would say the takbir (Allah is most great) seven times in the first rak'ah and five times in the second rak'ah on the day of the breaking of the fast and on the day of sacrifice (on the occasion of both the 'Id prayers, the two festivals)

English translation · Sunan Abu Dawud