صحيح البخاري

Narrated `Uqba bin `Umar and Abu Mas`ud:

Allah's Messenger (ﷺ) pointed with his hand towards Yemen and said, "(True) Belief is Yemenite, towards here (i.e. the Yemenite, had True Belief and embraced Islam readily). Certainly sternness and mercilessness are the qualities of those who are loud and at the base of the tails of camels, where the two horns of Satan will appear. Such qualities belong to the tribes of Rabi`a and Mudar."