Makkot 8 - Negligent, Inadvertent , and Grossly Negligent Killing
A negligent killer runs away to one of the cities of refuge, where he lives in exile until the death of the High Priest. In the city he is safe, but once outside, the avenger of blood - a close relative of the victim - is allowed to kill him. If the killing was a complete accident, the killer is not punishable at all, but if it was gross negligence, then the city of refuge does not protect him.
When one is killed by the " wood of the ax ", Rabbi Yehudah the Prince understands it as a woodchip , but the Sages say that it means that an axe-head slipped off the wooden handle. Therefore, if the victim was killed by the axe-head, Rabbi Yehudah classifies this as gross negligence, when the killer does not go into exile, because it does not help him, but the Sages say that this is exactly the case of the exile. If the death was caused by a woodchip from the tree that is being chopped, then according to Rabbi Yehudah the killer is exiled, but according to the Sages he is free from punishment, because the killing was inadvertent.
Art: Childe Hassam - Woodchopper, 1902