John Gill Commentary Numbers 35:27

"and the avenger of blood find him without the border of his city of refuge, and the avenger of blood slay the manslayer; he shall not be guilty of blood," — Numbers 35:27 (ASV)

And the revenger of blood find him without the borders of the
city of his refuge
Without the suburbs, fields, and vineyards belonging to it:

and the revenger of blood kill the slayer ;
being exasperated against him, and to avenge the blood of his relation on him:

he shall not be guilty of blood ;
or be reckoned murderer, or die for it.