It is narrated about Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that he said: "Shall I not show you the place about which the Prophet (peace and blessings be upon him) said: 'I think the Beast of the Earth will emerge from it'?" Then Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) struck with his staff the crevice in Mount Safa and said: "That creature will have feathers and fur (or fine down). One third of it will come out at the speed of a swift horse running for three days and three nights. It will pass by the people, and they will flee from it to the mosques, and it will say to them: 'Do you think the mosques will save you from me?' Then it will begin to mark them. The people will be brought to the markets, and it will say: 'O disbeliever! O believer!'"
Abu Ya'la recorded it. Its chain contains Layth bin Abi Sulaym, who is a mudallis (one who conceals defects in the chain). The rest of its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الفتن - أعاذنا الله منها / 12575