Génesis 17:11 Midrash: Midrash Tanchuma, Vayikra Rabbah, Pirkei DeRabbi Eliezer & Bereshit Rabbah

This is the animal that you shall eat: This is what the verse stated (Psalms 40:9), "To do Your will, my God, have I desired; and your Torah is in my innards." Happy is Israel, as He gave a commandment for each and every one [of their] limbs, as there are two hundred and forty-eight limbs in a man. And therefore we say every day, "Blessed are You, Lord, our God, King of the World, who has created man with wisdom, and created in him many holes and many channels." The numerical equivalent of many channels (chalulim, chalulim) is two hundred and forty-eight - that is like the tally of limbs in a man. In the head, do not round the corner of your heads" (Leviticus 19:27). On the flesh, "A gash for a soul you shall not place into your flesh" (Leviticus 19:28). And also the commandment of circumcision, as it is stated (Genesis 17:11), "And you shall circumcise the flesh of your foreskin." And further that He sealed his name, which is Sha-dai, into the Children of Israel - the shin in the noses, the dalet in the hand and the yod in the circumcision. The shin in the noses, so that they not accept nor derive benefit from that which is stolen; the dalet in the hand, so that the give and take (buying and selling) of a man be with propriety and not with theft; and the yod in the circumcision, so that a man not sin, etc."

When the Holy One, blessed be He, told Abraham: Walk before Me, and be thou wholehearted (Gen. 17:1), Abraham began to wonder. He said to himself: “Surely, until now I have been whole in body, but if I circumcise myself I shall be incomplete. There are five prepuces, four in a man and one on a tree. The prepuce of the ear, as it is written: Behold, their ear is uncircumcised (Jer. 6:10); the prepuce of the heart, as it is written: Remove the obduracy of your heart (Deut. 10:16); the prepuce of the tongue, as it is said: Of uncircumcised lips (Exod. 6:12); the prepuce of the flesh, as it is written in this verse: Ye shall be circumcised in the flesh of your foreskin (Gen. 17:1). If I should circumcise any one of these prepuces, my organs will be incomplete.” The Holy One, blessed be He, asked him: “Why do you believe that you are whole? In fact you lack five limbs. Before you were circumcised, your name was Abram: The alef in your name is one, the bet two, the resh two hundred, and the mem forty, and that totals two hundred and forty-three. However, Man’s limbs total two hundred and forty-eight. Circumcise yourself and you will be whole.” After he was circumcised, the Holy One, blessed be He, said to Him: No longer is your name Abram; henceforth it will be Abraham (ibid., v. 5). He added a heh, which equals five, to his name, making a total of two hundred forty-eight, corresponding to the number of limbs in the human body. Hence Scripture says: Be thou whole.

Rav Huna bar Kapara said: Abraham our patriarch sat and expounded: Orla is stated regarding a tree and orla is stated regarding man.¹⁹The foreskin, which is removed during a circumcision, is also called orla. Just as orla that is stated regarding the tree is in the place where it produces fruit, so orla that is stated regarding man is in the place where he produces offspring. Rabbi Ḥanin ben Pazi said: Did Abraham already know a fortiori inferences and verbal analogies? Rather, He hinted it to him: “I will establish My covenant between Me and you [and will multiply you exceedingly]” (Genesis 17:2), [implying that it is in] the place from which he procreates.
Rabbi Yishmael taught: The Holy One blessed be He sought to have the priesthood emerge from Shem, as it is stated: “Malkitzedek king of Shalem [brought out bread and wine and he was a priest of God, the Most High]” (Genesis 14:18). When he gave precedence to the blessing of Abraham over the blessing of the Omnipresent,²⁰“And he blessed him and said: Blessed be Abram…and blessed be God, the most High…” (Genesis 14:19–20). Abraham said to him: ‘Does one give precedence to blessing the servant over blessing the master?’ The Holy One blessed be He removed it from him and gave it to Abraham, as it is stated: “The utterance of the Lord to my master” (Psalms 110:1) and it is written thereafter: “The Lord has taken an oath, and He will not renounce it; you are a priest forever by My decree [divrati], like Malkitzedek” (Psalms 110:4); due to the speech [diburo] of Malkitzedek. That is what is written: “Blessed is Abram to God, the Most High, master of heaven and earth” (Genesis 14:19).
Rabbi Yishmael and Rabbi Akiva, Rabbi Yishmael says: Abraham was a High Priest; that is what is written: “The Lord has taken an oath, and He will not renounce it; you are a priest forever”; and it is written: “You shall circumcise the flesh of your foreskin” (Genesis 17:11). From where would he circumcise? If he would circumcise from the ear, he would remain ineligible to sacrifice. If he would circumcise from the heart, he would remain ineligible to sacrifice. If he would circumcise from the mouth, he would remain ineligible to sacrifice. From where would he circumcise and be eligible to sacrifice? One must say this is a mitzva of [the tip of] the body.²¹It must be that it is the foreskin that is removed, after which the individual remains unblemished.
Rabbi Akiva says: There are four instances of orla. Orla is stated regarding the ear: “Their ear is obstructed [arela]” (Jeremiah 6:10); orla regarding the mouth, as it is stated: “I am one of obstructed lips [aral sefatayim]” (Exodus 6:30); it is stated regarding the heart, as it is stated: “The entire house of Israel is of uncircumcised heart [arlei lev]” (Jeremiah 9:25). And it is written: “Walk before Me and be perfect” (Genesis 17:1). Where should he circumcise? If he would circumcise from the ear he would not be perfect. If he would circumcise from the mouth he would not be perfect. Where could he circumcise and be perfect? One must say this is the male organ.
Nagda said: It is written: “And one who is eight days old [shall be circumcised]” (Genesis 17:12). From where should he be circumcised? If from the ear, he will not be able to hear. If from the mouth, he will not be able to speak. If from the heart, he will not be able to think. From where could he be circumcised and be able to hear, speak, and think? One must say this is the male organ. Rabbi Tanḥuma said: Nagda’s [reasoning] is the most logical.
“An uncircumcised male who will not circumcise [the flesh of his foreskin]” (Genesis 17:14); Rabbi Yudan in the name of Rabbi Yitzḥak, and Rabbi Berekhya in the name of Rabbi Yitzḥak, and they taught it in the name of Rabbi Yosei ben Ḥalafta: “An uncircumcised male” – is there an uncircumcised female? Rather, at the place that one sees him and knows whether he is male or female, that is where one circumcises him.