وَإِذَا دَخَلَ الرَّجُلُ فِي صَلَاتِهِ كَبَّرَ، وَرَفَعَ يَدَيْهِ مَعَ التَّكْبِيرِ حَتَّى يُحَاذِيَ بِإِبْهَامَيْهِ شَحْمَتَي أُذُنَيْهِ.
Meaning: When a man begins his prayer, he pronounces takbir and raises both hands together with it until his thumbs are level with the earlobes.
The wording links the verbal opening to the sunnah movement of raising the hands and states a concrete physical reference point.