Yahya related to me from Malik from Abd ar-Rahman ibn Harmala al-Aslami from Said ibn al-Musayyab that the Messenger of Allah, mayAllah bless him and grant him peace, said, "What separates us from thehypocrites is being present at isha and subh. They cannot do it," orwords to that effect.
App reference: Book 8, Hadith 5
USC-MSA web (English) reference: Book 8, Hadith 5
Arabic reference: Book 8, Hadith 292