Mishkat al-Masabih #742

Ibn ‘Umar said that God’s Messenger used to raise his hands opposite his shoulders when he began prayer and when he said the takbir before bowing; and when he raised his head after bowing he raised them in the same way and said, “God listens to him who praises Him. To Thee, our Lord, be the praise!” But he did not do that when he prostrated himself. (Bukhari and Muslim.)