Musnad Abu Ya'la al-Mawsili 156:7

Abu Yusuf al-Jizi narrated to us, Abdullah ibn al-Walid narrated to us, Abbad ibn Kathir narrated to us, from Abu Umayyah Abd al-Karim, who said: al-Hasan ibn Abi al-Hasan narrated from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "Allah does not accept a prayer except with purification, nor charity from spoils of war taken dishonestly (ghulul)."