Whose land may not be sold?
Radak: The Leviyim's, and all the more so the Kohanim may not sell from their inheritance to a Yisrael. Malbim ? even though it is an inheritance for them, they may not sell it.
What is the meaning of "v'Lo Yamer"?
Rashi: He will not switch them for another land.
Why does it add "v'Lo Ya'avir"?
Malbim: It will not pass [to another Shevet] via a daughter who inherits 1 .
Perhaps if she married a Yisrael, her father's family inherits her, as if she had no husband or children. Alternatively, the verse forbids her to marry a Yisrael. All will be Tzadikim then, and fulfill this (refer to 45:8:3:1*), and it will never occur that a girl married b'Heter (she had brothers), and afterwards they died without children, and she inherited. (PF)
It is written Ya'avor, and we pronounce it Ya'avir!
Radak: The portion Lo Ya'avor (will not pass to another). The Kohen or Levi is commanded Lo Ya'avir (not to transfer it).
Why is it called "Reishis ha'Aretz"?
Radak: It is called Terumas ha'Aretz, and Terumah is Reishis.
What do we learn from "Ki Kodesh la'Shem"?
Radak: All this is Kodesh, even though one is more Kodesh than another, all is Kodesh la'Shem, for it is the inheritance of those who serve Hashem.
Malbim: This is like it says "v'Sede Migrash Areihem Lo Yimacher 1 " (Vayikra 25:34). This hints to other laws in the Torah, e.g. we may not convert a Migrash (refer to 46:17:1:1) to a field?
What is his source that the Torah's Isur is due to Kedushah? That verse concludes "Ki Achuzas Olam Hu Lahem"! (PF)