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