Musnad Ahmad 5:155

Sulayman ibn Dawud narrated to us, Abd al-Rahman—meaning Ibn Abi al-Zinad—narrated to us, from Musa ibn Uqbah, from Abd Allah ibn al-Fadl ibn Abd al-Rahman ibn Fulan ibn Rabi'ah ibn al-Harith ibn Abd al-Muttalib al-Hashimi, from Abd al-Rahman al-A'raj, from Ubayd Allah ibn Abi Rafi', from Ali ibn Abi Talib, from the Messenger of Allah (may Allah bless him and grant him peace): "That when he stood for the obligatory prayer, he would say the takbir and raise his hands level with his shoulders. He would do the same when he finished his recitation and intended to bow, and he would do it when he raised his head from bowing. He would not raise his hands in any part of his prayer while he was sitting. And when he stood up from two prostrations, he would raise his hands likewise and say the takbir."