Numbers 35:21

“Or in enmity smite him with his hand, that he die, etc.] Give him a blow with his fist, on some part of his body where life is most in danger, and which issues in death: he that smote him shall surely be put to death, for he is a murderer; and therefore, according to the original law, ought to die, without reprieve or pardon; and notwithstanding this law made for cities of refuge, which were to be denied him: the revenger of blood shall slay the murderer when he meeteth him: that is, when he is condemned, as both the Targums of Onkelos and Jonathan interpret it, after a hearing and trial of his case.”

“The sense is: Inasmuch as to take another man’s life by any means whatsoever is murder, and exposes the murderer to the penalty of retaliation; so, if the deed is done in hostility, it is in truth actual murder, and the murderer shall be slain; but if it be not done in hostility, then the congregation shall interpose to stop the avenger’s hand. Numbers 35:19 When he meeteth him - Provided, of course, it were without a city of refuge. Numbers 35:24 The case of the innocent slayer is here contemplated. In a doubtful case there would necessarily have to be a judicial decision as to the guilt or innocence of the person who claimed the right of asylum. Numbers 35:25 The homicide was safe only…”