Musnad Ahmad 30:2182

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Muhammad ibn Ziyad, who said: Marwan used to appoint Abu Hurairah over Medina. He said: So whenever he saw a person dragging his lower garment, he would strike with his foot, then say: "The Amir has come, the Amir has come." Then he would say: Abu al-Qasim (peace and blessings of Allah be upon him) said: "Allah will not look at the one who drags his lower garment out of pride."