Parashas Masei · Passuk 35:6 · TT note 1
Chabad.org — English translation + Rashi
Torah Temimah points to Makkos 10a / 13a (TT note on “וַעֲלֵיהֶם תִּתְּנוּ”).
English: What is the difference between the six cities of refuge and the forty-two [other Levitical] cities? The former receive [the manslayer] whether knowingly or unknowingly; the latter receive only knowingly, not unknowingly. In the former one does not pay rent to the Levites; in the latter one does pay rent to the Levites.
Halakhic distinction between the six designated cities of refuge and the remaining Levitical cities that also absorb.
Only the six primary cities of refuge absorb an unintentional killer even without his knowledge; the other forty-two Levitical cities absorb only when he knows and chooses them, and there he must pay the Levites rent.