וְעָרֵי֙ הַלְוִיִּ֔ם בָּתֵּ֖י עָרֵ֣י אֲחֻזָּתָ֑ם גְּאֻלַּ֥ת עוֹלָ֖ם תִּהְיֶ֥ה לַלְוִיִּֽם׃
But as for the cities of the Levites, the houses of the cities of their possession, the Levites shall have a perpetual right of redemption.
Read kabbalistic (mystical) interpretation of Leviticus 25:32: and classical mystical sources.