Sahih Bukhari
Characteristics of Prayer
Volume: 001 / Book Number: 012 / Hadith Number: 703
Narrated 'Abdullah bin 'Umar:
I saw that whenever Allah's Apostle stood for the prayer, he used to raise both his hands up to the shoulders, and used to do the same on saying the Takbir for bowing and on raising his head from it and used to say, "Sami a-l-lahu Liman hamida". But he did not do that (i.e. raising his hands) in prostrations.