Saeed bin As summoned Abu Musa al-Ashari and Huzaifa bin Yaman, may Allah be pleased with them both, and asked, "How did the Messenger of Allah ﷺ make the takbir during the prayers of Eid al-Fitr and Eid al-Adha?"Abu Musa replied, "He would say four takbirs, the same as his takbirs over funerals."Huzaifa confirmed his statement.Abu Ayesha said, "I never forgot his words 'the same as his takbirs over funerals' afterward." Abu Ayesha was present with Saeed bin As.
حدثنا زيد بن الحباب قال ثنا ابن ثوبان عن أبيه عن مكحول قال
أن سعيد بن العاص دعا أبا موسى الأشعري وحذيفة بن اليمان رضي الله تعالى عنهما فقال كيف كان رسول الله ﷺ يكبر في الفطر والأضحى فقال أبو موسى كان يكبر أربع تكبيرات تكبيره على الجنائز وصدقه حذيفة فقال أبو عائشة فما نسيت بعد قوله تكبيره على الجنائز وأبو عائشة حاضر سعيد بن العاص
Its chain of transmission is hasan, on account of Ibn Thawban, whose name is Abdul-Rahman bin Thabit bin Thawban. They criticized his memory, and he had become impaired in his later years. As for his father, he is a well-known trustworthy narrator. And Abu Ayesha the Umayyad is accepted among them. This hadith recurs frequently regarding Abu Musa. See Sunan Bayhaqi 3/289.