Hazrat Aamir narrates that a case was presented before Hazrat Ali (may Allah be pleased with him) in which an ox gored a donkey with its horn and killed it. Upon this, Hazrat Ali (may Allah be pleased with him) said: If the ox attacked the donkey and killed it, then its owner will be held liable; but if the donkey attacked the ox and then the ox killed it, then there will be no liability.