Leviticus 24:19-21
24:19 If a man inflicts an injury on his fellow citizen, just as he has done it must be done to him –
24:20 fracture for fracture, eye for eye, tooth for tooth – just as he inflicts an injury on another person that same injury must be inflicted on him.
24:21 One who beats an animal to death must make restitution for it, but one who beats a person to death must be put to death.