Sunan Abi Dawud 1149
سنن أبي داود#1149SahihNarrated 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)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautHasan Lighairihi
Zubair Ali ZaiHasan
In-book reference: 2:760