Ibrahim (al-Nakha'i) narrates: Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said the takbir when he began the prayer and did like this. (The narrator Mis'ar, while relating this, demonstrated by raising both his hands up above his chest.)
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9169