Musnad Ahmad 31:591

Isma'il narrated to us, Sa'id ibn Yazid informed us, from Abu Nadra, from Abu Sa'id al-Khudri, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Among your caliphs there will be a caliph who will scoop up wealth in handfuls, and he will not count it by number."