(83) باب رَفْعِ الْيَدَيْنِ فِي التَّكْبِيرَةِ الأُولَى مَعَ الاِفْتِتَاحِ سَوَاءً
Narrated Salim bin `Abdullah:
My father said, "Allah's Messenger (ﷺ) 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 hamidah, Rabbana wa laka l-hamd." And he did not do that (i.e. raising his hands) in prostrations.
Reference: Sahih al-Bukhari 735
In-book reference: Book 10, Hadith 129
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 12, Hadith 702