Abdullah narrates from his father, Sayyiduna Abdullah bin Umar (may Allah be pleased with him): We were with the Prophet (peace and blessings be upon him) on the morning of Arafah. Some of us were saying takbir and some talbiyah, but we were saying takbir. The narrator says: I said: By Allah, it is amazing of you; why did you not ask him: What did you see the Messenger of Allah (peace and blessings be upon him) doing?
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة العيدين / 6272