Musannaf Ibn Abi Shayba 18:980

Abu Bakr narrated to us, he said: Ibn Fudayl narrated to us, from Layth, from ‘Amr ibn Shu‘ayb, from his father, from his grandfather ‘Abdullah ibn ‘Amr, who said: A man was driving a donkey and was riding upon it, so he struck it with a stick he had with him. A splinter flew off from it and hit his (the donkey's) eye, and it gouged it out. That was raised to ‘Umar ibn al-Khattab, and he said: "It is one of the hands of the Muslims; it did not strike anyone out of aggression." So he placed the blood money for its eye upon his ‘aqilah (male relatives).