When the Messenger of Allah ﷺ stood at the end of two rak’ahs, he uttered the takbir (Allah is most great) and raised his hands.  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا قَامَ مِنَ الرَّكْعَتَيْنِ كَبَّرَ وَرَفَعَ يَدَيْهِ  

When the Messenger of Allah ﷺ stood for offering the obligatory prayer, he uttered the takbir (Allah is most great) and raised his hands opposite to his shoulders; and he did like that when he finished recitation (of the Qur'an) and was about to bow; and he did like that when he rose after bowing; and he did not raise his hands in his prayer while he was in his sitting position. When he stood up from his prostrations (at the end of two rak'ahs), he raised his hands likewise and uttered the takbir (Allah is most great) and raised his hands so as to bring them up to his shoulders, as he uttered the takbir in the beginning of the prayer.  

عَنْ رَسُولِ اللَّهِ ﷺ أَنَّهُ كَانَ إِذَا قَامَ إِلَى الصَّلاَةِ الْمَكْتُوبَةِ كَبَّرَ وَرَفَعَ يَدَيْهِ حَذْوَ مَنْكِبَيْهِ وَيَصْنَعُ مِثْلَ ذَلِكَ إِذَا قَضَى قِرَاءَتَهُ وَأَرَادَ أَنْ يَرْكَعَ وَيَصْنَعُهُ إِذَا رَفَعَ مِنَ الرُّكُوعِ وَلاَ يَرْفَعُ يَدَيْهِ فِي شَىْءٍ مِنْ صَلاَتِهِ وَهُوَ قَاعِدٌ وَإِذَا قَامَ مِنَ السَّجْدَتَيْنِ رَفَعَ يَدَيْهِ كَذَلِكَ وَكَبَّرَ  

I saw the Prophet ﷺ raise his hands when he uttered the takbir (Allah is most great), when he bowed and when he raised his head after bowing until he brought them to the lobes of his ears.  

رَأَيْتُ النَّبِيَّ ﷺ يَرْفَعُ يَدَيْهِ إِذَا كَبَّرَ وَإِذَا رَكَعَ وَإِذَا رَفَعَ رَأْسَهُ مِنَ الرُّكُوعِ حَتَّى يَبْلُغَ بِهِمَا فُرُوعَ أُذُنَيْهِ  

If I were in front of the Prophet ﷺ, I would see his armpits. Ibn Mu'adh added that Lahiq said: Do you not see, AbuHurayrah could not stand in front of the Prophet ﷺ while he was praying. Musa added: When he uttered the takbir, he raised his hands.  

أَبُو هُرَيْرَةَ لَوْ كُنْتُ قُدَّامَ النَّبِيِّ ﷺ لَرَأَيْتُ إِبْطَيْهِ زَادَ ابْنُ مُعَاذٍ قَالَ يَقُولُ لاَحِقٌ أَلاَ تَرَى أَنَّهُ فِي الصَّلاَةِ وَلاَ يَسْتَطِيعُ أَنْ يَكُونَ قُدَّامَ رَسُولِ اللَّهِ ﷺ وَزَادَ مُوسَى يَعْنِي إِذَا كَبَّرَ رَفَعَ يَدَيْهِ  

The Messenger of Allah ﷺ taught us how to pray. He then uttered the takbir (Allah is most great) and raised his hands; when he bowed, he joined his hands and placed them between his knees. When this (report) reached Sa'd, he said: My brother said truly. We used to do this; then we were later on commanded to do this, that is, to place the hands on the knees.  

عَبْدُ اللَّهِ عَلَّمَنَا رَسُولُ اللَّهِ ﷺ الصَّلاَةَ فَكَبَّرَ وَرَفَعَ يَدَيْهِ فَلَمَّا رَكَعَ طَبَّقَ يَدَيْهِ بَيْنَ رُكْبَتَيْهِ قَالَ فَبَلَغَ ذَلِكَ سَعْدًا فَقَالَ صَدَقَ أَخِي قَدْ كُنَّا نَفْعَلُ هَذَا ثُمَّ أُمِرْنَا بِهَذَا يَعْنِي الإِمْسَاكَ عَلَى الرُّكْبَتَيْنِ