The Messenger of Allah ﷺ used to raise his hands until they were in level with his shoulders when he started to pray, and when he raised his head from bowing he did likewise, and when he said: Sami' Allahu liman hamidah (Allah hears the one who praises Him)" he said: "Rabbana wa lakal-hamd (Our Lord, to You be praise)" and he did not raise his hands between the two prostrations.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَرْفَعُ يَدَيْهِ إِذَا دَخَلَ فِي الصَّلاَةِ حَذْوَ مَنْكِبَيْهِ وَإِذَا رَفَعَ رَأْسَهُ مِنَ الرُّكُوعِ فَعَلَ مِثْلَ ذَلِكَ وَإِذَا قَالَ سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ قَالَ رَبَّنَا لَكَ الْحَمْدُ وَكَانَ لاَ يَرْفَعُ يَدَيْهِ بَيْنَ السَّجْدَتَيْنِ