سنن النسائي

It was narrated that Ibn Umar said: "I saw the Messenger of Allah (ﷺ), when he stood to pray, raise his hands until they were in level with his shoulders, then he said the takbir. He did that when he said the Takbir before bowing, and he did that when he raised his head from bowing and said: 'Sami Allahu liman hamidah (Allah hears those who praise Him).' Bu he did not do that during the prostration."