Deuteronomy 19:7

וַאֲשֶׁר יָבֹא אֶת־רֵעֵהוּ בַיַּעַר לַחְטֹב עֵצִים וְנִדְּחָה יָדוֹ בַגַּרְזֶן לִכְרֹת הָעֵץ וְנָשַׁל הַבַּרְזֶל מִן־הָעֵץ וּמָצָא אֶת־רֵעֵהוּ וָמֵת הוּא יָנוּס אֶל־אַחַת הֶעָרִים־הָאֵלֶּה וָחָֽי

as when a man goeth into the forest with his neighbour to hew wood, and his hand fetcheth a stroke with the axe to cut down the tree, and the head slippeth from the helve, and lighteth upon his neighbour, that he die; he shall flee unto one of these cities and live;

פֶּן־יִרְדֹּף גֹּאֵל הַדָּם אַחֲרֵי הָרֹצֵחַ כִּי־יֵחַם לְבָבוֹ וְהִשִּׂיגוֹ כִּֽי־יִרְבֶּה הַדֶּרֶךְ וְהִכָּהוּ נָפֶשׁ וְלוֹ אֵין מִשְׁפַּט־מָוֶת כִּי לֹא שֹׂנֵא הוּא לוֹ מִתְּמוֹל שִׁלְשֽׁוֹם

lest the avenger of blood pursue the manslayer, while his heart is hot, and overtake him, because the way is long, and smite him mortally; whereas he was not deserving of death, inasmuch as he hated him not in time past.

וְאִם־יַרְחִיב יְהוָה אֱלֹהֶיךָ אֶת־גְּבֻלְךָ כַּאֲשֶׁר נִשְׁבַּע לַאֲבֹתֶיךָ וְנָתַן לְךָ אֶת־כָּל־הָאָרֶץ אֲשֶׁר דִּבֶּר לָתֵת לַאֲבֹתֶֽיךָ

And if the LORD thy God enlarge thy border, as He hath sworn unto thy fathers, and give thee all the land which He promised to give unto thy fathers—

כִּֽי־תִשְׁמֹר אֶת־כָּל־הַמִּצְוָה הַזֹּאת לַעֲשֹׂתָהּ אֲשֶׁר אָנֹכִי מְצַוְּךָ הַיּוֹם לְאַהֲבָה אֶת־יְהוָה אֱלֹהֶיךָ וְלָלֶכֶת בִּדְרָכָיו כָּל־הַיָּמִים וְיָסַפְתָּ לְךָ עוֹד שָׁלֹשׁ עָרִים עַל הַשָּׁלֹשׁ הָאֵֽלֶּה

if thou shalt keep all this commandment to do it, which I command thee this day, to love the LORD thy God, and to walk ever in His ways—then shalt thou add three cities more for thee, beside these three;