Esau's Milah

The Rabbenu Yona, in his commentary to Sanhedrin, says that Esau did bris milah. He explains the reason is that he would be included in the command to Avraham that his descendants should do bris milah. Even though Esau is excluded from כי ביצחק ולא כל יצחק, that was only established later on. The idea of the establishment of ולא כל יצחק was not said yet is cited by the Briskor Rav in the name of Rav Chayim to explain why the Rambam (Melachim 10:7) cites a different verse to exclude Esau from milah, שהרי יצחק אמר ליעקב ויתן לך את ברכת אברהם לך ולזרעך, מכלל שהוא לבדו זרעו של אברהם המחזיק בדתו ודרכו הישרה והם המחוייבין במילה. Why does he not cites ולא כל יצחק? Because the possuk itself doesn't say Esau is out, maybe Yaakov is out; it is only from the fact that Yaakov is given the mantle to carry on the legacy of Avraham that we know to read ביצחק ולא כל יצחק to exclude Esau, but that is not a given in itself. 

The Daas Zekanim (25:25) cites a Midrash כשראהו אביו אמר עדיין לא נבלע בו דמיו ולא רצה למולו לשמונה ימים כדאמרינן גבי מעשה דשתי נשים שבאו לפני נתן הבבלי וכו׳. כשעבר שנה או שנתיים וראה יצחק שלא החליף מראיתו ידע שזו תולדתו ואפ״ה לא מל אותו אמר הואיל ולא מלתי אותו לשמנה כמוני אמתין עד שיהיה בן י״ג כמו ישמעאל אחי ואמול אותו וכשהיה בן י״ג שנה הוא עכב בעצמו ולא רצה למול והיינו דכתיב אם לא דם שנאת ודם ירדפך. According to the Midrash Esau never obtained a bris milah. But it is clear that Yitzchak did want to give him a bris milah. According to Rabbenu Yona presumably there was no danger in doing the milah, however, if there is a machlokes, it may be explained in multiple ways. 

The Mizrachi (Shemos 4:24) asks how Moshe could delay giving milah to his son, even if there is sakanah, there is no heter of וחי בהם for a gentile to not put himself in danger for the fulfillment of a mitzvah? He clearly assumes that וחי בהם is not said for a gentile, and hence, for a positive fulfillment of a mitzvah, there is no exemption even for life-threatening situations. The Parashas Derachim (Derech Ha'esarim #2) presents several points of argument against the Mizrachi's assertion. He argues on his principle, for he holds even without וחי בהם one does not have to put themselves in danger to fulfill a mitzvah, וחי בהם is only necessary to remove a possible limmud from the cardinal sins that one would have to give up their life (see more about the discussion in הרחבות לפניני הלכה.) Another point he raises is that even if the Mirachi is correct, how can Moshe put someone else in danger to fulfill his obligation? (The Chemdas Yisrael mitzvah 215) says this objection hinges on the nature of the father who does the milah for his son. If it is the obligation of the father, the Parashes Derachim is right, that wouldn't allow him to put his child in danger but if the mitzvah is on the father to fulfill the obligation of his son since he is to young to do it himself, then the father is just acting as the agent of his son who would be obligated himself to put himself in danger to fulfill his obligation and the father can do the milah for him.)  Either one of these points would be in play regarding Yitzchak giving a milah to Esau.  

According to the Midrash why did Yitzchak not do the bris on Esau once he saw there was no more danger, why did he wait untill he was 13? Rabbi Shulman has a fancy approach here.    

The simple read of the Ramban (Lech Lecha 17:6) איננו נכון בעיני שיבשרנו בעת ברית המילה על עשו, והוא אינו מקיים המילה וגם לא נצטוה עליה, כמו שדרשו בסנהדרין (בבלי סנהדרין נ״ט:) כי ביצחק – ולא כל יצחק sounds like Esau did not have any command of milsh. However, he may be referring to after it was established ולא כל יצחק which was not at birth. Either way, the Ramban assumes that Esau did not have a bris at all like the Midrash.