Negative commandment · Lo Ta’aseh #295 of 613
Not to take a ransom from a murderer
שלא ליקח כופר מן הרוצח
The verse · Bamidbar 35:31
וְלֹא־תִקְחוּ כֹפֶר לְנֶפֶשׁ רֹצֵחַ אֲשֶׁר־הוּא רָשָׁע לָמוּת כִּי־מוֹת יוּמָת
“Moreover you shall take no ransom for the life of a murderer, who is guilty of death: but he shall be surely put to death.”
The Rambam’s words
Not to take a ransom from a murderer, as [Numbers 35:31] states: "Do not take a ransom for the life of a murderer."
שלא ליקח כופר מן הרוצח, שנאמר "ולא תקחו כופר לנפש רוצח" (במדבר לה, לא).
Why · Sefer HaChinuch #412
Not to take ransom to save the murderer from the death penalty
“And the root of this commandment is well-known — as if the rulers of the land allowed to take ransom from the hand of the murderer, it would come out that anyone greater and wealthier than his fellow would kill him if he got angry at him and give his ransom.”
Who & when
“And [it] is practiced at the time of the [Temple] by males and females, as at this time we have no involvement with capital punishments.”
Where in the Mishneh Torah
Hilchot Murderer and the Preservation of Life הלכות רוצח ושמירת נפש