Musnad Ahmad 30:3723

'Ali ibn Hafs narrated to us, Waraqa informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurayrah, who said: The Messenger of Allah (ﷺ) said: "By Him in Whose hand is my soul, it would not please me that I have gold like this [mountain of] Uhud, such that three days pass over me and I still have a dinar of it, except for something I set aside to pay off a debt of mine."