When the Prophet of Allah ﷺ began the prayer, he would raise his hands. When he bowed, he would do the same. When he raised his head from bowing, he would do the same. And when he raised his head from prostration, he would do the same, meaning he would raise his hands.
أخبرنا محمد بن المثنى قال حدثنا معاذ بن هشام قال حدثني أبي عن قتادة عن نصر بن عاصم
أن نبي الله ﷺ كان إذا دخل في الصلاة رفع يديه وإذا ركع فعل مثل ذلك وإذا رفع رأسه من الركوع فعل مثل ذلك وإذا رفع رأسه من السجود فعل مثل ذلك كله يعني رفع يديه