Land granted to those who serve in the Temple carries a unique, permanent sanctity. The rules governing these specific estates establish an absolute ban on changing their ownership, ensuring that the designated areas remain forever devoted to their sacred purpose.
The priests and Levites are strictly forbidden from selling any portion of their granted land to the rest of the Israelites. Although this territory is given to them as an inheritance, they do not possess the right to sell it [מלבי״ם]. Furthermore, they are not allowed to trade or exchange their original inheritance for a different piece of property. The restriction on transferring the land is two-fold: the physical land itself cannot pass into different hands, and the priests or Levites are actively forbidden from giving it away [רד״ק]. This strict rule also ensures that a daughter who inherits land cannot transfer it to a different tribe [מלבי״ם].
This sacred area holds the status of being the first of the land. This concept mirrors a holy offering, much like the first portion of grain that is set aside for the priests before regular tithes are taken [מצודת דוד, רד״ק]. Because it represents primacy and holiness, this special status will never be removed from the area. The underlying reason for all these restrictions is that the land is holy to God. Since the entire estate belongs to God's servants and is entirely sacred, it would be highly improper to treat it as ordinary property or allow it to fall into the hands of outsiders [מצודת דוד, רד״ק]. Ultimately, these rules act as a direct continuation of the broader Torah laws that prevent the selling, exchanging, or repurposing of the cities and open spaces given to the Levites [מלבי״ם].