Musnad Ahmad 27:660

Muhammad ibn Abdullah al-Zubayri narrated to us, Sufyan narrated to us, from Abdullah ibn Dinar, I heard Ibn Umar saying: The Messenger of Allah, peace and blessings of Allah be upon him, said—and he pointed with his hand toward the east—and said: "Verily, the tribulations are from here, verily the tribulations are from here, verily the tribulations are from here, from where the horn of Satan rises."