Sunan Abi Dawud Book 2, Hadith 334
He saw that when the Prophet(ﷺ) stood up to pray he raised his hands till they were in front of his shoulders and placed his thumbs opposite his ears; then he uttered the Takbir (Allah is most great).
I was a small boy and I did not understand the prayer of my father. So Wa’Il b. ‘Alqamah reported Wa’il b. Hujr as saying: I offered prayer along with the Messenger of Allah (ﷺ). He used to raise his hands when he pronounced the takbir (Allah is most great), then pulled his garment around him, then placed his right hand on his left, and entered his hands in his garment. When he was about to bow he took his hands out of his garment, and then raised them. And when he raised his head after bowing, he raised his hands. He then prostrated himself and placed his face (forehead on the ground) between his hands. And when he raised his head after prostration, he also raised his hands until he finished his prayer. Muhammad (a narrator) said: I mentioned it to al-Hasan b. Abu al-Hasan who said: This is how the Messenger of Allah(ﷺ) offered prayer; some did it and others abandoned it.
Abu Dawud said: This tradition has been narrated by Hammam from ibn Juhadah, but he did not mention the raising of hands after he raised his head at the end of the prostration.
Wa’il b.Hujr said that he saw the Messenger of Allah(ﷺ) raise his hands when he uttered the takbir (Allah is most great).