Musnad Abu Ya'la al-Mawsili 147:63

Sa'id ibn al-Ash'ath narrated to us, 'Isa ibn Sadaqah ibn 'Abbad al-Yashkuri informed me, he said: I entered with my father to Anas ibn Malik, and we said to him: "Narrate to us a hadith that Allah may benefit us with." I heard him say: "Whoever among you is able to die while having no debt upon him, let him do so. For I saw the Prophet of Allah, may Allah bless him and grant him peace, and a funeral of a man was brought to him, and upon him was a debt. He said: 'I will not pray over him until you guarantee his debt, for my prayer over him will benefit him.' They did not guarantee his debt, and he did not pray over him. He said: 'He is held hostage in his grave.'"