Huzaifa bin Usayd reported,
The Beast will emerge from the most sacred of mosques. While people are sitting, the earth will resound, and while they are in that state, it will split open.Ibn Uyayna said, "It will emerge at the time when the Imam departs from Muzdalifah. The forerunner of the pilgrims was appointed only to inform people that the Beast has not yet emerged."
Azami 16084
Hasanعن حذيفة بن أسيد- أراه رفعه- قال
تخرج الدابة من أعظم المساجد حرمة، فبينا هم قعود إذ رنت الأرض، فبينا هم كذلك إذ تصدعت. قال ابن عيينة: تخرج حين يسري الإمام من جمع، وإنما جعل سابق الحاج ليخبر الناس أن الدابة لم تخرج.
No references are available.
Tabarani narrated it in Al-Awsat (1657) from Ahmad (that is, Ibn Nadr Askari), who said, Hamza bin Saeed Marwazi told us, who said, Sufyan bin Uyayna told us, from Ibn Jurayj, from Abdullah bin Ubayd bin Umayr, from Abu Tufayl, and he mentioned it.Tabarani said, "No one narrated this hadith from Ibn Jurayj except Sufyan, and Hamza bin Saeed narrated it alone."Its isnad is hasan because of Hamza bin Saeed Marwazi, for his hadith is hasan.Haythami said in Al-Majma (78), "Tabarani narrated it in Al-Awsat, and its narrators are trustworthy."The scholars differed regarding the place where this beast will emerge, but the soundest report is that it will emerge from Makkah, and this is what the hadiths and reports indicate.As for the description of this beast, its nature and its form, the correct view is that no one knows it except Allah 
, because no mention of its description has come in the sahih texts.The reports that have come describing its features and form are all conjecture and guesswork, and even though some of them have been attributed to the companions, they are not sound.