Prayer (Kitab Al-Salat): Details of Commencing Prayer
Dawud :: Book 3 : Hadith 815
Narrated Mu'adh ibn Abdullah al-Juhani:
A man of Juhaynah told him that he had heard the Prophet (peace_be_upon_him) reciting "When the earth is shaken" (Surah 99) in both rak'ahs of the morning prayer. But I do not know whether he had forgotten, or whether he recited it on purpose.