Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 1262
Narated By Qays ibn Amr : The Apostle of Allah (pbuh) saw a person praying after the congregational prayer at dawn was over. The Apostle of Allah (pbuh) said: There are two rak'ahs of the dawn praye (i.e. the prescribed rak'ahs). The man replied: I did not pray the two rak'ahs before the dawn prayer. Hence I offered them now. The Apostle of Allah (pbuh) kept silent.