Musnad Ahmad 175:21

'Ali ibn Bahr narrated to us, he said: 'Isa ibn Yunus narrated to us, from Zakariyya, from Muhammad ibn 'Abd al-Rahman ibn Sa'd ibn Zurarah, that the son of Ka'b ibn Malik narrated to him, from his father, that the Prophet, peace and blessings of Allah be upon him, said: "Two hungry wolves sent into a flock of sheep are not more destructive to them than a man's greed for wealth and status is to his religion."