Sunan Abi Dawud Book 2, Hadith 412
The prophet (ﷺ) used to stand in the rak’ah of prayer so much so that no sound of steps heard.
We asked Khabbab: Did the Messenger of Allah (ﷺ) recit (the Quran) in the noon and afternoon prayers? He replied: Yes. We then asked: How did you know this? He said: By the shaking of his beard, may peace be upon him.
’Umar said to Sa’d: people complain against you for everything, even for prayer. He replied: I prolong the first two rak’ahs of prayer and make the last two rak’ahs brief; I do not fall short of following the prayer offered by the Messenger of Allah(May peace be upon him). He said: I think so about you.