Sahih al-Bukhari 735
Narrated Salim bin 'Abdullah:
My father said, "Allah's Apostle used to raise both his hands up to the level of his shoulders when opening the prayer, and on saying the Takbir for bowing, and on raising his head from bowing he used to do the same and then say "Sami a-l-lahu Liman hamida, Rabbana walaka-l-hamd.", and he did not do that (i.e. raising his hands) in prostrations.
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِيهِ، أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَرْفَعُ يَدَيْهِ حَذْوَ مَنْكِبَيْهِ إِذَا افْتَتَحَ الصَّلاَةَ، وَإِذَا كَبَّرَ لِلرُّكُوعِ، وَإِذَا رَفَعَ رَأْسَهُ مِنَ الرُّكُوعِ رَفَعَهُمَا كَذَلِكَ أَيْضًا وَقَالَ " سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ، رَبَّنَا وَلَكَ الْحَمْدُ ". وَكَانَ لاَ يَفْعَلُ ذَلِكَ فِي السُّجُودِ.