Halakhah su Levitico 25:32

To not change the open areas of the Levites: Not to change the open areas of the cities of the Levites and their fields - meaning to say, that a city may not be made into an open area, nor an open area into a city, a field into an open area, nor an open area into a field. And the law is the same about an open area (another textual variant: field) into a city and a city into an open area (another textual variant: field) - that one may not change anything about their content. And this matter is well-known, as the Torah commanded (Numbers 35:2-7) that the other tribes cede certain cities to the tribe of Levi; and these are forty-eight cities, with the six cities of refuge that were among them. And it also commanded that there be in these cities a thousand ells of open area - meaning a place open for space and beauty for the city; and two thousand ells beyond that for the sake of fields and vineyards, and this is also of the beauty of the city and from that which it needs, as it is explained in Sotah 27b. And this prevention comes about this, that these matters never be changed. And concerning this it states (Leviticus 25:34), "And the fields of open areas of their cities shall not be sold" - meaning, shall not be changed. As it is not speaking about actual selling, since it is explicitly written in Scripture (Leviticus 25:32), "a perpetual redemption shall there be for the Levites" - which implies that they are permitted to sell them.