Sahih Al Bukhari Hadith Number 738

Narrated `Abdullah bin `Umar: I saw Allah’s Messenger (peace be upon him) opening the prayer with the Takbir and raising his hands to the level of his shoulders at the time of saying the Takbir, and on saying the Takbir for bowing he did the same; and when he said, “Sami`a l-lahu liman hamidah “, he did the same and then said, “Rabbana wa laka lhamd.” But he did not do the same on prostrating and on lifting the head from it.”

10  Call to Prayers (Adhaan)
Hadith number 738
Volume no 1
Chapter: 85 (To what level should one raise one’s hand.)