Abu Dawud Book 2, Hadith Number 1255.
Chapter : On observing the sunan prayer at dawn lightly.
Narated By Abu Hurairah : I heard the Prophet (PBUH) recite in both rak’ahs of the dawn: “say: We believe in Allah, and in the revelation given to us” (ii. 136). This is in the first rak’ah. In the second rak’ah (he recited) this verse: “O Lord, we believe in that which Thou hast revealed and we follow the messenger, so write us down with those who bear witness” (iii. 53) or he recited: “Surely, We have sent thee with truth as a bearer of good news and as a warner, and thou wilt not be called upon to answer for the companions of the flaming fire” (ii. 119). Al-Darawardi doubted (which of the verses he recited).