Musnad Ahmad 27:1715

Ya'qub narrated to us, Ibn Akhi Ibn Shihab narrated to us, from his uncle, Salim ibn 'Abdullah narrated to me, that 'Abdullah said: When the Messenger of Allah (peace and blessings of Allah be upon him) stood for prayer, he would raise his hands until they were level with his shoulders, then he would say the takbir. Then, when he intended to bow, he would raise them until they were level with his shoulders, and he would say the takbir while they were in that position, then he would bow. Then, when he intended to raise his back, he would raise them until they were level with his shoulders, then he would say: "Sami' Allahu liman hamidah" (Allah hears those who praise Him). Then he would prostrate, and he would not raise his hands during the prostration. He would raise them in every rak'ah and for every takbir he said before bowing, until his prayer was completed.