Sahih Bukhari Volume 2, Book 20, Hadith Number 220.

Narated By ‘Aisha : (The mother of the faithful believers) Allah’s Apostle (in his last days) used to pray sitting. He would recite while sitting, and when thirty or forty verses remained from the recitation he would get up and recite them while standing and then he would bow and prostrate. He used to do the same in the second Raka. After finishing the Prayer he used to look at me and if I was awake he would talk to me and if I was asleep, he would lie down.