Messenger of Allah 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 Rabiʿa and Mudar." (Using translation from Bukhārī 3302)
"إِن الإِيمانَ ههُنا، إِن الإِيمانَ ها هنا، وإِن القسوةَ وغلَظَ القلوبِ في الفدَّادِين ، عندَ أصولِ أذنابِ الإِبل، حيثُ يطلعُ قرنُ الشيطانِ في ربيعَةَ ومضرَ".