Negative commandment · Lo Ta’aseh #227 of 613
Not to sell a field in Eretz Yisrael in perpetuity
שלא למכור שדה בארץ ישראל לצמיתות
The verse · Vayikra 25:23
וְהָאָרֶץ לֹא תִמָּכֵר לִצְמִתֻת כִּי־לִי הָאָרֶץ כִּי־גֵרִים וְתוֹשָׁבִים אַתֶּם עִמָּדִי
“The land shall not be sold for ever: for the land is mine; for you are strangers and sojourners with me.”
The Rambam’s words
Not to sell a field in Eretz Yisrael in perpetuity, as [Leviticus 25:23] states: "Do not make a permanent sale of the land."
שלא למכור שדה בארץ ישראל לצמיתות, שנאמר "והארץ, לא תימכר לצמיתות" (ויקרא כה,כג).
Why · Sefer HaChinuch #339
That we not sell a field in the Land of Israel in perpetuity
“It is from the roots of the commandment from the angle of the simple understanding that G-d, may He be blessed, wanted to inform His nation that everything is His; and in the end everything will return to those to whom He wanted to give it at first — for the earth is His, as it is written (Exodus 19:5), “for all the earth is Mine.””
Who & when
“And [it] is practiced by males and females in the Land of Israel when its inhabitants are upon it; as all the matters of the Jubilee are only [applied] at the time when its inhabitants are upon it, as we wrote above.”
Where in the Mishneh Torah
Hilchot Sabbatical Year and the Jubilee הלכות שמיטה ויובל