Nafi', the freed slave of Ibn Umar (may Allah be pleased with them both), said: I attended the prayers of Eid al-Fitr and Eid al-Adha with Abu Hurayrah (may Allah be pleased with him). He would say seven takbirs in the first rak'ah before the recitation, and five takbirs in the second rak'ah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة العيدين / 6179