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)." (PT)
English reference (PT): Vol. 1, Book 5, Hadith 803 (PT)
Arabic reference (PT): Book 5, Hadith 852 (PT)