It is narrated from Sayyiduna Wa'il bin Hujr (may Allah be pleased with him); he said: "I prayed behind the Messenger of Allah (peace and blessings be upon him). When he (peace and blessings be upon him) began the prayer, he said the takbir and raised his hands until they were level with his (peace and blessings be upon him) ears."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18264