Musnad Ahmad 30:2689

Yazid narrated to us, Muhammad informed us, from Abu Salamah, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "I would not love for myself to have the equivalent of Mount Uhud in gold, such that three nights pass over me while I still have any of it, and I find someone to accept it from me, except for what I would set aside for a debt that is upon me."