Musnad Ahmad 30:366

Yazid narrated to us, Muhammad ibn Ishaq informed us, from Musa ibn Yasar, from Abu Hurayrah, who said: Abu al-Qasim said: "If I had gold equal to [the mountain of] Uhud, it would please me that I spend it in the way of Allah, and that there does not come upon it a third [night] while I have a dinar or a dirham of it remaining, except for something that I reserve for a debt that is upon me."