Positive commandment · Mitzvat Aseh #138 of 613
To free all land in the Jubilee year
ליתן גאולה לארץ בשנת היובל
The verse · Vayikra 25:24
וּבְכֹל אֶרֶץ אֲחֻזַּתְכֶם גְּאֻלָּה תִּתְּנוּ לָאָרֶץ
“And in all the land of your possession you shall grant a redemption for the land.”
The Rambam’s words
To free all land in the Jubilee year, as [Leviticus 25:24] states: "For all your ancestral lands, there will be redemption for the land."
ליתן גאולה לארץ בשנת היובל, שנאמר: "ובכול, ארץ אחוזתכם, גאולה, תיתנו לארץ" (ויקרא כה,כד).
Why · Sefer HaChinuch #340
Returning land to its owners on the Jubilee
“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 and at the time that the Jubilee is practiced.”
Where in the Mishneh Torah
Hilchot Sabbatical Year and the Jubilee הלכות שמיטה ויובל