It is narrated from Sayyiduna Uqbah bin Amr (Abu Mas'ud) (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) looked towards Yemen and said: "Faith is Yemeni, and hardness and coarseness of heart are among the loud-voiced herdsmen who live by the tails of the camels, in Rabi'ah and Mudar, where the two horns of Satan rise."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14649