Musnad Ahmad 937:106

Waki’ narrated to us, al-A’mash narrated to us, from Sulayman ibn Mushir, from Kharashah ibn al-Hurr, from Abu Dharr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said to me: "O Abu Dharr, look at the most elevated man in the mosque." He said: So I looked, and behold, there was a man wearing a fine garment. He said: I said, "This one." He said: He said to me: "Look at the most lowly man in the mosque." He said: So I looked, and behold, there was a man wearing worn-out clothes. He said: I said, "This one." Then the Messenger of Allah (peace and blessings of Allah be upon him) said: "This one is better in the sight of Allah on the Day of Resurrection than a fill of the earth like that one."