Musnad Abu Ya'la al-Mawsili 2:72

Muhammad ibn Ali ibn al-Hasan ibn Shaqiq narrated to us, he said: I heard my father say: Al-Husayn ibn Waqid narrated to us, from al-A’mash, from Habib ibn Abi Thabit, that Abd al-Rahman ibn Abi Layla narrated to him, he said: I went out with Umar ibn al-Khattab to Makkah. The governor of Makkah, Nafi’ ibn Alqama—and he was named after a paternal uncle of his called Nafi’—met us. He (Umar) said: "Whom did you appoint as a successor over Makkah?" He said: "I appointed Abd al-Rahman ibn Abza as a successor over it." He said: "You resorted to a man from the *mawali* (freedmen) and appointed him as a successor over those who are there from the Quraysh and the Companions of the Messenger of Allah, may Allah bless him and grant him peace?" He said: "Yes, I found him to be the most proficient of them in the Book of Allah, and Makkah is a land that is frequented, so I liked for them to hear the Book of Allah from a man who is a good reciter." He said: "Yes, what I have seen is that Allah raises some people by the Quran and lowers others by the Quran, and indeed Abd al-Rahman ibn Abza is among those whom Allah has raised by the Quran."