Negative commandment · Lo Ta’aseh #111 of 613
Not to redeem a field that has been dedicated
שלא לפדות שדה החרם
The verse · Vayikra 27:28
אַךְ־כׇּל־חֵרֶם אֲשֶׁר יַחֲרִם אִישׁ לַה׳ מִכׇּל־אֲשֶׁר־לוֹ מֵאָדָם וּבְהֵמָה וּמִשְּׂדֵה אֲחֻזָּתוֹ לֹא יִמָּכֵר וְלֹא יִגָּאֵל כׇּל־חֵרֶם קֹדֶשׁ־קׇדָשִׁים הוּא לַה׳
“Notwithstanding no devoted thing, that a man shall devote to the Lord of all that he has, both of man and beast, and of the field of his possession, shall be sold or redeemed: every devoted thing is most holy to the Lord.”
The Rambam’s words
Not to redeem a field that has been dedicated, as [Leviticus, ibid.] states: "It shall not be redeemed."
שלא לפדות שדה החרם, שנאמר "לא ייגאל" (ויקרא כז,כח).
Why · Sefer HaChinuch #359
That a dedicated field not be redeemed
“It is from the roots of the commandment [that it is] because Israel is the nation that G-d chose from all the other nations for His service and to recognize His Name, and they are not under the rule of the constellations that G-d apportioned to all the other nations.”
Who & when
“And there is no doubt that these two negative commandments — which are “it shall not be sold” and “it shall not be redeemed” — are practiced today according to the opinion of Rambam, may his memory be blessed, as I wrote above: [In the case of] one who dedicates land or movable objects outside the Land at this time, it is given to the priests.”
Where in the Mishneh Torah
Hilchot Appraisals and Devoted Property הלכות ערכים וחרמין