Whenever the Messenger of Allah ﷺ stood up after the first two units of prayer, he would say the takbir and raise his hands.
حدثنا عثمان بن أبي شيبة ومحمد بن عبيد المحاربي قالا حدثنا محمد بن فضيل عن عاصم بن كليب عن محارب بن دثار
كان رسول الله ﷺ إذا قام من الركعتين كبر ورفع يديه
[Its isnad is sahih] Ahmad narrated it: 2/145, from Muhammad bin Fudayl bin Ghazwan, through his chain, affirming the raising of the hands before and after ruku.