Musnad Ahmad 790:117

Mu'adh ibn Hisham narrated to us, my father narrated to me, from Qatadah, from Abu Nadrah, from Imran ibn Husayn, that a servant of some poor people cut off the ear of a servant of some wealthy people. His family came to the Prophet, may Allah bless him and grant him peace, and said: "O Prophet of Allah, we are poor people." So he did not impose anything upon him.