The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 1592
Alqama b. Waqqas reported: I asked 'A'isha how the Messenger of Allah (may peace be upon him) did in the two rak'ahs as he (observed them) sitting. She said: He would recite (the Qur'an) in them, and when he intended to bow, he would stand up and then bowed.