When the Prophet ﷺ started to pray he would say: "Subhanakallahumma, wa bihamdika tabarakasmuka wa ta'ala jadduka wa la ilaha ghairuk (Glory and praise be to You, O Allah. Blessed be Your name and exalted be Your majesty, there is none worthy of worship except You.)"
أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا افْتَتَحَ الصَّلاَةَ قَالَ سُبْحَانَكَ اللَّهُمَّ وَبِحَمْدِكَ تَبَارَكَ اسْمُكَ وَتَعَالَى جَدُّكَ وَلاَ إِلَهَ غَيْرُكَ