Numbers 35:18

With a hand-weapon It made no difference with what kind of weapon he was killed, whether it was of iron, wood, or stone. If he was killed wittingly and knowingly, it was murder, and the guilty person was to die for it. For though perhaps he had no intention to kill the person, yet he ought to have moderated his passion, and could not be ignorant that such an instrument was capable of inflicting a deadly wound.