He saw his father raise his hands when he said the opening takbir, when he was about to bow, and when he raised his head from bowing. So I asked him about that, and he stated that he had seen the Messenger of Allah ﷺ doing this.
حدثنا محمد بن جعفر حدثنا شعبة عن جابر سمعت
أنه رأى أباه يرفع يديه إذا كبر وإذا أراد أن يركع وإذا رفع رأسه من الركوع فسألته عن ذلك فزعم أنه رأى رسول الله ﷺ يصنعه