Abu Dawud Book 2, Hadith Number 1032.

Narated By Al-Mughirah ibn Shu’bah : Ziyad ibn Ilaqah said: Al-Mughirah ibn Shu’bah led us in prayer and he stood up at the end of two rak’ahs. We said: Glory be to Allah; he also said: Glory be to Allah, and he proceeded. When he finished the prayer and gave the salutation, he made two prostrations of forgetfulness. When he turned (to us) he said: I saw the Apostle of Allah (PBUH) doing so as I did.