Musnad Ahmad 30:1640

Zayd ibn al-Hubab narrated to us, Mu'awiyah ibn Salih narrated to us, he said: Abu Maryam narrated to me, that he heard Abu Hurayrah saying: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The sovereignty is in Quraysh, the judiciary is in the Ansar, the Adhan is in the Abyssinians, and the swiftness is in Yemen." And Zayd said once, while memorizing it: "And the trustworthiness is in the Azd."