Abu Dawud Book 2, Hadith Number 1289.
Chapter : Prayer in the forenoon.
Narated By Simak : I asked Jabir b. Samurah: Did you sit in the company of the Apostle of Allah (PBUH)? He replied: Yes, very often. He would not stand from the place he prayed the dawn prayer till the sunrise. When the sun rose, he would stand (to pray in the forenoon).