Musnad Abu Ya'la al-Mawsili 160:54

Abu Bakr ibn Zanjawayh narrated to us, 'Amr ibn al-Rabi' narrated to us, Yahya ibn Ayyub narrated to us, from 'Umarah ibn Ghaziyyah, from 'Abdullah ibn Muhammad ibn 'Aqil ibn Abi Talib, from Abu Murrah, the freed slave of 'Aqil, from Abu Hurayrah, from the Prophet (may Allah bless him and grant him peace), who said: "Two hungry, ferocious wolves let loose among a flock of sheep—one at the beginning of it and the other at the end of it—do not cause more corruption than a man’s [desire] for his religion [being corrupted by] his love for worldly status and wealth."