ENOfficial
Abu Humaid as-Sa‘idi said that when God’s Messenger stood up to pray, he faced the qibla, raised his hands and said, “God is most great." Ibn Majah transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَبِي حُمَيْدٍ السَّاعِدِيِّ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا قَامَ إِلَى الصَّلَاةِ اسْتَقْبَلَ الْقِبْلَةَ وَرَفَعَ يَدَيْهِ وَقَالَ: الله أكبر. رَوَاهُ ابْن مَاجَه
sunnah.com