Musannaf Ibn Abi Shayba 3:3317

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: ‘Abdullah ibn ‘Abd al-Rahman ibn Ya’la al-Ta’ifi narrated to us, from ‘Amr ibn Shu’ayb, from his father, from his grandfather, that the Prophet, peace and blessings of Allah be upon him, performed twelve takbirs in the ‘Eid: seven in the first [rak’ah] and five in the last.