The New John Gill Exposition of the Entire BibleNumbers 35:26
But if the slayer shall at any time come without the border of
the city of his refuge…
Which seems to be the three thousand
cubits assigned to every city of the Levites, and so to the cities of
refuge; and which, according to the Jewish writers, were a refuge, as
the city itself; and it is said F24,
``he, that kills a man there, is killed for him, but though the
border is a refuge, the slayer does not dwell in it, as it is
said. (Numbers 35:25) , "he shall abide in it", but not in its
whither he was fled;
on account of manslaughter.
F24 Maimon. Hilchot Rotzeach, c. 8. sect. 11. Misn. Maccot, c. 2. sect. 7.