Two Types Of Milah

Rashi at the end of Lech Lecha(in some editions,) quotes a midrash in Vayerah (49:2,) מִיָּד נָטַל אַבְרָהָם סַכִּין וְהָיָה אוֹחֵז בְּעָרְלָתוֹ וּבָא לַחְתֹּךְ וְהָיָה מִתְיָרֵא שֶׁהָיָה זָקֵן, מֶה עָשָׂה הַקָּדוֹשׁ בָּרוּךְ הוּא שָׁלַח יָדוֹ וְאָחַז עִמּוֹ, וְהָיָה אַבְרָהָם חוֹתֵךְ, שֶׁנֶּאֱמַר (נחמיה ט, ז ח): אַתָּה ה' הָאֱלֹהִים אֲשֶׁר בָּחַרְתָּ בְּאַבְרָם וגו', וְכָרוֹת לוֹ הַבְּרִית אֵין כְּתִיב כָּאן אֶלָּא וְכָרוֹת עִמּוֹ, מְלַמֵּד שֶׁהָיָה הַקָּדוֹשׁ בָּרוּךְ הוּא אוֹחֵז בּוֹ.  There is another Midrash at the end of Lech Lecha (47:9) that says נִמּוֹל אַבְרָהָם, אָמַר רַבִּי אַבָּא בַּר כַּהֲנָא הִרְגִּישׁ וְנִצְטָעֵר כְּדֵי שֶׁיִּכְפֹּל לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא שְׂכָרוֹ. אָמַר רַבִּי לֵוִי מָל אַבְרָהָם אֵין כְּתִיב כָּאן אֶלָּא נִמּוֹל, בָּדַק אֶת עַצְמוֹ וּמָצָא עַצְמוֹ מָהוּל. אָמַר רַבִּי בֶּרֶכְיָה בְּהַהִיא עִתָּא אֲקֵיל רַבִּי אַבָּא בַּר כַּהֲנָא לְרַבִּי לֵוִי, אֲמַר לֵיהּ שַׁקְּרָנָא כַּזְבָּנָא אַתְּ, אֶלָּא הִרְגִּישׁ וְנִצְטָעֵר כְּדֵי שֶׁיִּכְפֹּל הַקָּדוֹשׁ בָּרוּךְ הוּא שְׂכָרוֹ.  According to Rebbe Levi, Avrohom didn't have to do the milah at all, Hashem did it.  How could Hashem do the milah for Avrohom, if he had a commandment to do milah, how did he fulfill the mitzvah?

By way of intro. I will share a peshat in a midrash from Rav Schwab.  The Tanchumah at the beginning of Titzaveh says יְלַמְּדֵנוּ רַבֵּנוּ, קָטָן לְכַמָּה נִמּוֹל? כָּךְ שָׁנוּ רַבּוֹתֵינוּ: קָטֹן נִמּוֹל לִשְׁמוֹנָה. מַה טַּעַם? כְּשֵׁם שֶׁנִּמּוֹל יִצְחָק אָבִינוּ.  The midrash is very difficult for what is the question, its an open possuk in Lech Lecha (17:12) וּבֶן־שְׁמֹנַ֣ת יָמִ֗ים יִמּ֥וֹל לָכֶ֛ם כׇּל־זָכָ֖ר לְדֹרֹתֵיכֶ֑ם or Tazria (12:3) בַיּ֖וֹם הַשְּׁמִינִ֑י יִמּ֖וֹל בְּשַׂ֥ר עָרְלָתֽוֹ.  And why does the midrash answer with the possuk of Avrohom doing the bris for Yitzchak, which is just a story, not with the possuk of the command?  And what is this doing in the beginning of Titzaveh?  Rav Shwab explains that the midrash knows when the action of circumcision is done.  However, the milah of the skin is merely an indicator of the milah of the heart.  The midrash wants to know when does the milah of the heart happen.  Is it possible for an eight day old kid to be have the תיקון הנפש done, or does that only come about when he obtains brains?  The midrash answers the possuk says (21:4) וַיָּ֤מׇל אַבְרָהָם֙ אֶת־יִצְחָ֣ק בְּנ֔וֹ בֶּן־שְׁמֹנַ֖ת יָמִ֑ים, obviously its Yitzchak, his son, just say וַיָּ֤מׇל אַבְרָהָם֙ אותו?  We see that already at eight days he is called Yitzchak, he has the nefesh and powers of a Yitzchak.  From here the midrash derives that the milah of the heart comes simultaneously with the milah of the skin.  How does this happen if he doesn't have any brains?  It's the zertizut of the father and mesiras nefesh that causes this תיקון הנפש to happen.  That's the דיוק of the possuk (ibid) כַּאֲשֶׁ֛ר צִוָּ֥ה אֹת֖וֹ אלקים, the word צִוָּ֥ connotes zerizut (Kiddushin 29a.)  That's why it appears in the beginning of Titzaveh, to pick up on this theme of zerizut.  

Now that we have established that milah is also a תיקון הנפש, we can revisit the above midrashim.  The possuk in Ekev (10:16) says וּמַלְתֶּ֕ם אֵ֖ת עָרְלַ֣ת לְבַבְכֶ֑ם וְעָ֨רְפְּכֶ֔ם לֹ֥א תַקְשׁ֖וּ עֽוֹד:  You shall circumcise the foreskin of your heart.  However, in Nitzavim (30:6) it says ומל ה' אלקיך אֶת־לְבָֽבְךָ֖ וְאֶת־לְבַ֣ב זַרְעֶ֑ךָ.  And the Lord, your God, will circumcise your heart and the heart of your offspring. It seems to be a contradiction, do you do the milah of the heart or does Hashem do it?  The alter Rebbe explains (Torah Or end of Lech Lecha,) that there are two levels of alah to be removed.  This is the arlah that can be removed through teshuvah; that is your obligation.  Then is is a more fine tuned and more delicate arlah that is beyond one's grasp to remove himself; that Hashem will do.  Based upon this we can say of course Avrohom did the actual milah as he was commanded, the midrash means that Avrohom also merited that Hashe removed the second layer of the arlah as well.  That is the intent that Avrohom was too old, he didn't have the strength to remove this addiotional layer of arlah, so Hashem helped him complete the job.