Musnad Ahmad 980:8

Abu Usamah narrated to us, Zaidah narrated to us, from al-A’mash, from Shaqiq, from ‘Uqbah ibn ‘Amr Abu Mas’ud, who said: The Messenger of Allah (peace and blessings of Allah be upon him) used to command us to give charity, so one of us would go and work as a porter, then he would come with a mudd (a small measure of grain). And indeed, some of them today have one hundred thousand. Shaqiq said: I saw that he was referring to himself.