Sahih Muslim Book 4, Hadith Number 782.

Chapter : The reciting of Takbir at the time of bowing and rising in prayer except rising after Ruku’ when it is said: Allah listened to him who praised Him.

Abu Huraira reported: A person entered the mosque and said prayer while the Messenger of Allah (may peace be upon him) was sitting in a nook (of the mosque), and the rest of the Hadith is the same as mentioned above, but with this addition: “When you get up to pray, perform the ablution completely, and then turn towards the Qibla and recite takbir (Allah-u-Akbar – Allah is the Most Great).”