Numbers 35:21

or in hostility struck him with his hand, so that he died, he who struck him shall surely be put to death. He is a murderer. The avenger of blood shall put the murderer to death when he meets him.

Or in enmity smite him with his hand, that he die: he that smote him shall surely be put to death; for he is a murderer: the revenger of blood shall slay the murderer, when he meeteth him.