Musnad Abu Ya'la al-Mawsili 42:357

Zuhayr narrated to us, Abdullah bin Yazid narrated to us, Haywah informed us, Salim bin Ghaylan informed me that he heard Darraj Abu al-Samh, that he heard Abu al-Haytham, that he heard Abu Sa'id al-Khudri saying: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "I seek refuge in Allah from disbelief and debt." A man said: "O Messenger of Allah, do you equate debt with disbelief?" He said: "Yes."