It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that when the Messenger of Allah (peace and blessings be upon him) stood for prayer he would raise both hands until they were level with his shoulders; then whenever he said the takbir he would raise his hands in the same way and bow; then when he intended to rise from bowing he would again raise his hands in the same way, until he raised them level with his shoulders; then he would say: 'Sami' Allahu liman hamidah' (Allah has heard the one who praised Him). He did not raise his hands in the prostrations, but he raised his hands with every takbir before bowing until his prayer was complete.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2541