Abu Dawud Book 2, Hadith Number 664.
Chapter : Not known.
Narated By Al-Bara’ ibn Azib : The Apostle of Allah (PBUH) used to pass through the row from one side to the other; he used to set out chests and shoulders in order, and say: Do not be irregular. And he would say: Allah and His angels bless those who are near the first rows.