It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that a boy belonging to some poor people cut off the ear of a boy belonging to some rich people. His family came to the Prophet (peace and blessings be upon him) and said: "O Messenger of Allah, we are poor." "So he (peace and blessings be upon him) did not impose any compensation on them."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15603