Musnad Ahmad

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) used to raise his hands to the level of his shoulders at the beginning of the prayer, and he would also raise his hands when going into bowing (ruku‘) and after raising his head from bowing. And the Noble Prophet (peace and blessings be upon him), after saying "Sami‘ Allahu liman hamidah," would say "Rabbana wa laka al-hamd." However, between the two prostrations, the Noble Prophet (peace and blessings be upon him) did not raise his hands.