Muwatta Imam Malik (Riwayat Ibn al-Qasim)

And with this same chain (it is narrated from Sayyiduna Ibn Umar, may Allah be pleased with them both) that he saw the Messenger of Allah, peace and blessings be upon him, pointing towards the east. He, peace and blessings be upon him, was saying: "Listen! Indeed, the trial is here, indeed, the trial is here, from where the horn of Satan (the great trial) will emerge."