Sahih Muslim 862
صحيح مسلم#862SahihIbn Umar reported that the Messenger of Allah (ﷺ), when he stood up for prayer, used to raise his hands apposite the shoulders and then recited takbir (Allah-o-Akbar), and when he was about to bow he again did like it and when he raised himself from the ruku' (bowing posture) he again did like it, but he did not do it at the time of raising his head from prostration
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 4:25