Abu Dawud Book 2, Hadith Number 815.
Chapter : Not known.
Narated By Mu’adh ibn Abdullah al-Juhani : A man of Juhaynah told him that he had heard the Prophet (PBUH) 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.