כִּֽי־תִשְׁמֹר֩ אֶת־כָּל־הַמִּצְוָ֨ה הַזֹּ֜את לַעֲשֹׂתָ֗הּ אֲשֶׁ֨ר אָנֹכִ֣י מְצַוְּךָ֮ הַיּוֹם֒ לְאַהֲבָ֞ה אֶת־יְהוָ֧ה אֱלֹהֶ֛יךָ וְלָלֶ֥כֶת בִּדְרָכָ֖יו כָּל־הַיָּמִ֑ים וְיָסַפְתָּ֨ לְךָ֥ עוֹד֙ שָׁלֹ֣שׁ עָרִ֔ים עַ֖ל הַשָּׁלֹ֥שׁ הָאֵֽלֶּה׃
если ты будешь соблюдать всю эту заповедь, чтобы исполнить ее, которую Я заповедую тебе сегодня, любить Господа, Бога твоего, и всегда ходить по Его путям—тогда добавь еще три города для себя, кроме этих трех;
Sforno
וירא אליו ה' באלוני ממרא, because this was where Avraham had circumcised himself at that time. His whole household had been circumcised with him at the time. This is where G’d manifested Himself as a sign that He stood by the covenant, similar to the verse at the beginning of Deuteronomy 29,9-11, commencing with the words אתם נצבים היום, and to Kings II 23,3 ויכרות לפני ה'. He appeared to Avraham seeing he was the individual most deserving to be the recipient of such a vision. We have a similar occurrence in Exodus 4,24 ויפגשהו ה', where G’d “met” with Moses without delivering an oral message. At that time G’d’s purpose was to ensure that Moses would circumcise his son, to maintain the covenant which was to be an eternal covenant with the descendants of Avraham as spelled out in Genesis 17,11-12. Perhaps this is the reason why a chair is prepared at the occasion of the circumcision (Pirkey de Rabbi Eliezer 29, as well as Zohar Bereshit 13,10) This chair alludes to the fact that hopefully, the presence of G’d will attend this marking of the sign of the covenant by a new member of the Jewish people.
Kli Yakar
And since these three caused the destruction and removal of the Divine Presence, therefore He commanded to distance them from the camp so they would not defile their camps, because wherever they are present, the Holy One, blessed be He, removes His Divine Presence from there, as the place is “called impure, impure.” A hint to this matter is the letter tet [numerical value nine] in the word tamei [impure], which alludes to bloodshed [shefichut damim] of one who is born after nine months. For this reason there were six cities of refuge, and it is written you shall add three more cities (Deuteronomy 19:9). In total nine, no more, for the reason that has been explained. The letter mem [numerical value 40] in tamei alludes to sexual immorality [giluy arayot], as the flood waters were 40 days because they troubled their Creator to form bastards during the 40 days of fetal formation. The letter alef in tamei alludes to idolatry [avodah zarah], which affects the oneness of the blessed God that is hinted at in the letter alef. Therefore, King David called the evil inclination impure (Sukkah 52b) because it caused him to stumble in all three: sexual immorality with Bathsheba, bloodshed with Uriah the Hittite, and idolatry as they learned (in Sanhedrin 107a) from the verse When David reached the summit (Second Samuel 15:32) — he sought to worship idolatry, etc. And there is also impurity in them, because idolatry defiles like a menstruant woman, as it says You will cast them away like a menstruous cloth (Isaiah 30:22). Therefore, He alluded in the removal of these three impure people to the removal of these three cardinal sins that cause the removal of the Divine Presence. And He connected to this section a man or woman who commits any sin to indicate that the removal of the impure is also because of their sin, as mentioned.
Tur HaArokh
כי ירחיב, “When He will expand (your boundaries);” Nachmanides makes the point that the term כי ירחיב, in this paragraph is not to be confused with the expression ואם ירחיב, in 19,8, where the Torah foresees further expansion of the Land of Israel [most commentators consider this a post messianic period. Ed.], but in verse 9 there we read –in connection with the establishment of cities of refuge- that more than the original three on the east bank of the Jordan must be added. In that context the meaning of the word is “when,” in the sense of after completion of the conquest. If the meaning of the two expressions were identical, eating meat that had not first been consecrated as an offering would not be permitted for the Israelites until after Joshua had completed the conquest and settled the people on their allocated parcels of land. In chapter 19 the line we quoted must be understood in connection with the paragraph at the beginning of that chapter, a paragraph which discusses changes that would occur after G’d has more or less wiped out the seven Canaanite tribes from the region of the West Bank of the Jordan. The need to establish additional cities of refuge begins only after the people have been settled. Verse 9 there may even refer to the time when the remainder of the ten tribes mentioned in G’d’s first promise to Avraham in Genesis chapter 15 have also been eliminated. In our verse the reference is to the beginning of the conquest, and according to Chulin 17, בשר תאוה, meat of animals that had been slaughtered without having been consecrated as offerings first, became permissible at once, as soon as settlement began. Even though, on the face of it, permission of such meat appears to be contingent on the owner living far away from the Temple, the words כי ירחק ממך המקום, “when the Temple is far away from you,” (verse 21) is not to be understood as actual physical distance of the individual concerned. The Torah means that when the Israelites, instead of living next to the Tabernacle, as they did for 40 years in the desert, will be scattered throughout the Land of Israel, it would not be practical to require them to come to Jerusalem, to the Temple every time they wanted to eat meat.