Musnad Ahmad 1153:188

Abdullah ibn Numayr narrated to us, Hajjaj narrated to us, from Qatadah, from Safiyyah bint Shaybah, from Aisha, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, for every people there is a source of support (maddah), and the source of support for Quraysh are their freedmen (mawali)."