Musnad Ahmad 27:1209

Abu al-Nadr narrated to us, Layth narrated to us, Nafi’ narrated to me, from Abdullah, that he heard the Messenger of Allah, may Allah bless him and grant him peace, while he was facing the east, saying: "Verily, the tribulation is from here; verily, the tribulation is from here, from where the horn of Satan rises."