Jmy' bin 'Umayr bin Afaq جميع بن عمير بن عفاق · Chapters on Virtues

that the Messenger of Allah (ﷺ) said: "Leadership is among the Quraish, and reasoning and judgment is among the Ansar, and the Adhan is among the Ethiopians, and the trust is among the Al-Azd." meaning Yemen.