Musnad Ahmad 30:2304

Qutaybah ibn Sa'id narrated to us, 'Abd al-'Aziz narrated to us, from Abu Suhayl ibn Malik, from his father, from Abu Hurayrah, that the Prophet (peace and blessings of Allah be upon him) said: "I would not love to have gold equal to Uhud, such that a third [day] comes upon me while I still have anything of it, except for something that I set aside for the repayment of a debt that is upon me."