Muhammadbin 'Amr bin 'Ata' said:
"I heard Abu Humaid As-Sa'idi say:'When the Messenger of Allah (ﷺ) stood up for prayer, he wouldfacethe prayer direction, raise his hands, and say: "Allahu Akbar(Allahis Most Great)." (FR)
English reference (FR): Vol. 1, Book 5, Hadith 803 (FR)
Arabic reference (FR): Book 5, Hadith 852 (FR)