Sunan An-Nasa'i - سنن النسائي
11. The Book of the Commencement of the Prayer - كتاب الافتتاح
86) Chapter: Raising the hands parallel to the shoulders before bowing
It was narrated from Salim that:
His father said: "I saw the Messenger of Allah (ﷺ) when he started to pray, raise his hands until they were parallel to his shoulders, (and he did that) when he bowed and when he raised his head from bowing."
86) باب رَفْعِ الْيَدَيْنِ لِلرُّكُوعِ حِذَاءَ الْمَنْكِبَيْنِ
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم إِذَا افْتَتَحَ الصَّلاَةَ يَرْفَعُ يَدَيْهِ حَتَّى يُحَاذِيَ مَنْكِبَيْهِ وَإِذَا رَكَعَ وَإِذَا رَفَعَ رَأْسَهُ مِنَ الرُّكُوعِ .