Positive commandment · Mitzvat Aseh #182 of 613
To prepare six refuge cities
להכין שש ערי מקלט
The verse · Devarim 19:3
תָּכִין לְךָ הַדֶּרֶךְ וְשִׁלַּשְׁתָּ אֶת־גְּבוּל אַרְצְךָ אֲשֶׁר יַנְחִילְךָ ה׳ אֱלֹהֶיךָ וְהָיָה לָנוּס שָׁמָּה כׇּל־רֹצֵחַ
“Thou shalt prepare the way, and divide the border of thy land, which the Lord thy God gives thee to inherit, into three parts, that every slayer may flee thither.”
The Rambam’s words
To prepare six refuge cities, as [Deuteronomy 19:3] states: "Prepare the way and divide into three [the boundary]...."
להכין שש ערי מקלט, שנאמר: "תכין לך, הדרך, ושילשת" (דברים יט,ג).
Why · Sefer HaChinuch #520
Prepare six cities of refuge
“The root of this commandment is well-known and clear — that it be so that the inadvertent killer not be killed by the blood avengers.”
Who & when
“And this commandment is practiced at the time that Israel is dwelling on their Land.”
Where in the Mishneh Torah
Hilchot Murderer and the Preservation of Life הלכות רוצח ושמירת נפש