Musnad Ahmad 30:3439

Yazid narrated to us, Ibn Abi Dhi'b informed us, from Abu al-Walid, from Abu Hurairah, from the Prophet (peace and blessings of Allah be upon him), who said: "I would not love for myself that I have a mountain of gold, such that three nights pass by me while I have a dinar of it remaining, except for something I set aside for a creditor."