[Machine] I have not seen the Messenger of Allah ﷺ stood up in prayer, whether obligatory or voluntary, except that he would raise his hands towards the sky, supplicate, and then say the takbir after following it. This was reported by Jarir from Ibn Ishaq in a hadith, and it was narrated in another hadith that he said: "When one of you begins the prayer, let him raise his hands and face the qibla with the palms of his hands, except that this narration is weak so I struck it out."  

مَا رَأَيْتُ رَسُولَ اللهِ ﷺ قَامَ فِي الصَّلَاةِ فَرِيضَةً وَلَا تَطَوُّعًا إِلَّا شَهَرَ يَدَيْهِ إِلَى السَّمَاءِ يَدْعُو ثُمَّ يُكَبِّرُ بَعْدُ تَابَعَهُ جَرِيرٌ عَنِ ابْنِ إِسْحَاقَ وَقَدْ رُوِيَ فِي حَدِيثٍ أَنَّهُ قَالَ إِذَا اسْتَفْتَحَ أَحَدُكُمُ الصَّلَاةَ فَلْيَرْفَعْ يَدَيْهِ وَلْيَسْتَقْبِلْ بِبَاطِنِهِمَا الْقِبْلَةَ إِلَّا أَنَّهُ ضَعِيفٌ فَضَرَبْتُ عَلَيْهِ