ENOfficial
Nafi‘ said that when Ibn ‘Umar began prayer he said the takbir and raised his hands; when he bowed he raised his hands; when he said, “God listens to him who praises Him” he raised his hands; and when he got up at the end of two rak'as he raised his hands. Ibn ‘Umar traced that back to the Prophet. Bukhari transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ نَافِعٍ: أَنَّ ابْنَ عُمَرَ كَانَ إِذَا دَخَلَ فِي الصَّلَاةِ كَبَّرَ وَرَفَعَ يَدَيْهِ وَإِذَا رَكَعَ رَفَعَ يَدَيْهِ وَإِذَا قَالَ سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ رَفَعَ يَدَيْهِ وَإِذَا قَامَ مِنَ الرَّكْعَتَيْنِ رَفَعَ يَدَيْهِ وَرَفَعَ ذَلِكَ ابْنُ عُمَرَ إِلَى نَبِيِّ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ. رَوَاهُ الْبُخَارِيُّ
sunnah.com