Numbers 35:12, 21, 24, 27

They shall be cities of refuge for you from the avenger, that the manslayer may not die until he stands before the congregation in judgment.

or in enmity he strikes him with his hand so that he dies, the one 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.

then the congregation shall judge between the manslayer and the avenger of blood according to these judgments.

and the avenger of blood finds him outside the limits of his city of refuge, and the avenger of blood kills the manslayer, he shall not be guilty of blood