It is narrated from Sayyiduna Wa'il bin Hujr (may Allah be pleased with him); he said: "I saw the Messenger of Allah (peace and blessings be upon him): when he (peace and blessings be upon him) began the prayer, he would raise his hands until they reached below his (peace and blessings be upon him) ears."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18266