Sunan Ibn Majah, Chapter: The Chapters on Tribulations

"The Messenger of Allah (saw) prayed one day, and made the prayer lengthy. When he finished we said (or they said): 'O Messenger of Allah, you made the prayer lengthy today.' He said: 'I offered a prayer of hope and fear. I asked Allah for three things for my nation, and He granted me two and refused one. I asked Him not to let my nation be destroyed by enemies from without, and He granted me that. And I asked Him not to let them be destroyed by drowning, and He granted me that. And I asked Him not to let them be destroyed by fighting among themselves, but He refused that.'"