Musannaf Ibn Abi Shayba 37:178

Husayn ibn Ali narrated to us, from Za'idah, from Abd al-Malik ibn Umayr, from Abdullah ibn Amr, who said: The Beast will emerge from Mount Ajyad during the Days of Tashriq while the people are in Mina. He said: That is why the driver of the pilgrims is greeted when he brings the people back safely.