וְכָל־אַנְשֵׁ֤י בֵיתוֹ֙ יְלִ֣יד בָּ֔יִת וּמִקְנַת־כֶּ֖סֶף מֵאֵ֣ת בֶּן־נֵכָ֑ר נִמֹּ֖לוּ אִתּֽוֹ׃ (פ)
И все жители его дома, родившиеся в доме и купленные на деньги иностранца, были обрезаны с ним.
Da'at Zekenim
וירא אליו ה' באלוני ממרא, “The Lord appeared to him at eloney mamre, etc.” According to Rashi, Mamre was the man who had advised Avraham strongly to carry out G–d’s command to circumcise himself. This is why this revelation took place while Avraham was on his property. The obvious question here is why someone of the stature of Avraham needed to consult with his friends about if and how to relate to G–d’s commandment. He had been tested as to his faith in Him on ten occasions, and he had passed all these tests without consulting with anyone, why would he suddenly feel the need to “consult” anyone? The answer clearly must be that Avraham did not “consult” with anyone in order to decide if to carry out G–d’s command; he only asked his friends if to perform this commandment on himself in the privacy of his tent or publicly, in order to demonstrate his loyalty to G–d’s command. His purpose in doing so publicly would be in order to encourage others to emulate his example. When the Torah described him as performing the act of circumcision בעצם היום הזה, (Genesis 17,23) these words mean: “in broad daylight, for all to see.” Mamre was given credit by G–d for having given Avraham this advice. A different interpretation of our verse: Avraham consulted with Mamre regarding the exact part of his body where the “circumcision” had to be performed. He therefore advised him to perform this operation on the organ that represented his masculinity. After all, G–d had restricted the performance of this rite to the males of the species. (17,10) He also advised him to commence with circumcising himself and his son Ishmael first. Once his slaves and friends would observe this, most of them would follow willingly without protest. The Torah testifies in chapter 17, verse 27 that all the members of Avraham’s household (including hired help) were circumcised on the same day that he was. If you were to ask why Mamre, himself, who gave Avraham this advice, did not have himself circumcised also, the answer is that eventually he did do so as reported in a Midrash.
Rambam
A good eye: We have explained many times that the matter of a good eye is sufficing and [that] a small appetite is carefulness and [that] a humble spirit is extreme humility as was explained in the chapter before this one (Rambam on Pirkei Avot 4:4). And the three [negative traits] that correspond to them are zeal to acquire money and that is an evil eye, and much desire and that is a broad appetite and arrogance and that is a haughty spirit. And these three virtues are publicized in Abraham, our father. And because of this, anyone who is found to have these virtues is called one of the students of Abraham, our father - as he followed his traits. And anyone within whom is found these three vices is of the students of Bilaam the evildoer - as he followed his traits. And I will mention the places in which are elucidated these virtues in Abraham and these vices in Bilaam, and they are all found in the Torah. Indeed, the sufficing of Abraham is in his saying to the king of Sedom (Genesis 14:23), "If from a thread to a sandal strap, and if I take from any of what is yours, etc." And that is the epitome of sufficing - that a man leave much money and not benefit from it, even a little bit. But his caution is his saying to Sarah on the day they came to Egypt (Genesis 12:11), "Behold, I have known that you are a woman of beautiful appearance." And the explanation comes that he did not fully look at her form besides that day - and that is the epitome of carefulness. And [it is also shown] in his saying about Hagar after he married her (Genesis 16:6), " Behold, your maidservant is in your hands - do to her as is good in your eyes." [This] shows that he did not wish to enjoy himself with her. And so [too] when Sarah requested from him to expel her with Yishmael such that he would be prevented from inclining towards [Hagar] for sexual matters, the verse testifies that it was only bad in his eyes about Yishmael, and that is its stating (Genesis 21:11), "And the matter was very bad in the eyes of Abraham on account of his son." These are all signs of carefulness. And, indeed, his humility is his stating (Genesis 18:27), "and I am dust and ashes." And Bilaam the evildoer's zeal for money was publicized and that is his coming from Aram Naharaim for the sake of the money with which he was hired to curse Israel. And that is His, may He be blessed, stating (Deuteronomy 23:5), "since he hired against you Balaam son of Beor, etc." And, indeed, his great desire in sexual matters is the reason for his advice to Balak that he set loose the women to be promiscuous with [the men of] Israel and to place known harlots [in front of them]. As were it not for the great desire that he had and that harlots were good in his eyes, he would not have commanded this - since the commands of people are only according to their opinions. As the good will not command to [do] evil, but will rather warn against it. And the language of Scripture (Numbers 31:16) is "They are the very ones against the children of Israel by the word of Bilaam, etc." And the sages said (Sanhedrin 105a) [that] Bilaam had sexual relations with his donkey. And there is no doubt about it that one with such an opinion will have actions [like] this. And indeed, his arrogance is his stating (Numbers 24:16), "Speaks the one who hears the words of God." And indeed that which it brought a proof about Bilaam from its stating (Psalms 55:24), "And You, God, will bring them down to the pit of destruction; the people of blood, etc." - [its] explanation is [that it is] because he was a man of blood - as he was the cause of the Israelites' death in the plague; and he was also a man of deceit in his creating a machination to bring about the evil. And its bringing a proof about the students of Abraham from its stating (Proverbs 8:21), "There is what for those that love Me to inherit, and their treasuries will I fill" is like that which He called him (Isaiah 41:8), "the seed of Abraham, the one I love."