Midrash su Genesi 17:21

These are the generations of Isaac, Abraham’s son: Abraham begot Isaac (Gen. 25:19). Scripture states elsewhere in allusion to this verse: The father of the righteous will greatly rejoice; and he that begetteth a wise child will have joy of him (Prov. 23:24). Concerning whom did Solomon make this statement? He said it about Isaac. When Isaac was born, the entire universe rejoiced; the heavens and the earth, the sun and the moon, the stars and the planets. Why did they rejoice? Because the world would not have survived had Isaac not been born, as it is said: If My covenant be not with day and night, if I have not appointed the ordinance of heaven and earth (Jer. 33:25). My covenant refers to Isaac, as it is said: I will establish My covenant with Isaac (Gen. 17:21).

THE TRIALS OF ABRAHAM (continued)
THE eighth trial (was as follows): "And when Abram was ninety-nine years old" (Gen. 17:1), the Holy One, blessed be He, said to him: Until now thou hast not been perfect before Me; but circumcise the flesh of thy foreskin, and "walk before me, and be thou perfect" (ibid.). Moreover, the foreskin is a reproach, as it is said, "For that is a reproach unto us" (Gen. 34:14), because the foreskin is more unclean than all unclean things, as it is said, "For henceforth there shall no more || come into thee the uncircumcised and the unclean" (Isa. 52:1). For the foreskin is a blemish above all blemishes. Circumcise the flesh of thy foreskin and be perfect.

Rabban Gamaliel said: Abraham sent and called for Shem, the son of Noah, and he circumcised the flesh of the foreskin of our father Abraham, and the flesh of the foreskin of Ishmael his son, as it is said, "In the selfsame day was Abraham circumcised, and Ishmael his son" (Gen. 17:26). "In the selfsame day" (means) in the might of the sun at midday. Not only that, but (it indicates) the tenth day of the month, the Day of Atonement. It is written in connection with the Day of Atonement, "Ye shall do no manner of work on that selfsame day, for it is a day of atonement" (Lev. 23:28); and in the present instance the text says, "In the selfsame day was Abraham circumcised" (Gen. 17:26). Know then that on the Day of Atonement Abraham our father was circumcised. Every year the Holy One, blessed be He, sees the blood of our father Abraham's circumcision, and He forgives all the sins of Israel, as it is said, "For on this day shall atonement be made for you, to cleanse you" (Lev. 16:30). In that place where Abraham was circumcised and his blood remained, there the altar was built, and therefore, "And all the blood thereof shall he pour out at the base of the altar" (Lev. 4:30). (It says also), "I said unto thee, In thy blood, live; yea, I said unto thee, In thy blood, live" (Ezek. 16:6).

… And He said to him ‘go away to the land of Moriah and bring him up there for a burnt offering’ (Bereshit 22:2) What is the land of Moriah? There is a whole bundle of Sages here, each saying their own answer. R’ Yanai says ‘what is Moriah? The place from which awe and fear (morah and yirah) go out to the world,’ “You are feared, O God, from Your Sanctuary…” (Tehillim 68:36) R’ Chiya the elder says ‘the land from which instruction (hora’ah) goes out to the world,’ as it says “…for out of Zion shall the Torah come forth…” (Yeshayahu 2:3) Another explanation: the land from which, in the future, the Holy One will teach that the wicked should descend to gehinnom, as it says “Like sheep, they are destined to the grave; death will devour them, and the upright will rule over them in the morning, and their form will outlast the grave…” From where? “…his dwelling place (zevul).” (Tehillim 49:15) Another explanation of the land of Moriah. R’ Yehoshua ben Levi said ‘the land from which the righteous teach (morim) and make decrees upon the Holy One which He does,’ as it says “…and David and the elders, covered with sackcloth, fell upon their faces. And David said to God, "Did I not say to count the people?…I beg that Your hand be against me and against my father's house, but not against Your people for a plague." (Divre HaYamim I 21:16-17) Another explanation of the land of Moriah. R’ Yehudah bar Padiiya said ‘Moriah - he said to Gd, where is it? He replied – to the land which I will show (mareh) you.’ Another explanation of Moriah. Avraham said to Gd, Master of the World! But am I fit to offer sacrifices? Am I a kohen? Let Shem the High Priest come and receive him from me. The Holy One replied to him – when you arrive at the place I will sanctify you and make you into a kohen. What is the meaning of Moriah? In exchange (temurah) for Shem. His replacement, as it says “He shall not exchange it or offer a substitute for it…” (Vayikra 27:10) Another explanation. What is Moriah? R’ Pinchas said ‘the land in which the master (maruto) of the world dwells,’ as it says “…and My eyes and My heart shall be there at all times.” (Melachim I 9:3) Another explanation. What is Moriah? R’ Shimon bar Yochai said ‘the land which was adorned opposite the altar above “…or cast down… (yaro yireh)” (Shemot 19:13) Another explanation. The land in which the incense is offered – “I will go to the mountain of myrrh (mor)…” (Shir HaShirim 4:6)

"And they came to the place which God had told him of; and Avraham built the altar there" (Gen. 22:9). And where was Itzchak? Said Rabbi Levi: he had taken and hidden him, saying, 'Lest he who sought to seduce him throw a stone at him and disqualify him from being a sacrifice.' "And Avraham built the altar there etc and bound Itzchak his son". Rabbi Hanina bar Itzchak said: As our father Avraham was binding his son Itzchak below, so the Holy One of Blessing was binding the [angel] princes of the heathens above. Yet they did not remain [bound]. For when Israel separated themselves in the days of Jeremiah the Holy One of Blessing said to them: ‘What do you think: that those fetters still exist?’ as it says, "For shall they be like tangled thorns (sirim)" (Nahum 1:10), which means: For are the Princes (sarim) to be tangled [i.e. bound] forever? No; for when they [the Israelites] are “drunken according to their drink” (Nahum 1:10), their fetters are broken, for it is written, "They shall be devoured as stubble fully dry" (Nahum 1:10). When our father Avraham stretched forth his hand to take the knife to slay his son, the angels wept, as it says, “Behold, their valiant ones [the angels] cry without — hutzah” (Isa. 33:7). What does ‘hutzah’ mean? R. ‘Azariah said: It is unnatural. It is unnatural that he should slay his son with his own hand. And what did they say? The highways lie wasted? (Isa. 33:8) — does not Avraham show hospitality to travelers? The wayfaring man ceased — shavat (Isa. 33:8) — as in the verse, It had ceased (hadal) for Sarah (Gen. 18:2). "He has broken the covenant" (Isa. 33:8), [similar to] “But My covenant will I establish with Itzchak” (Gen. 17:21). “He has despised the cities (Isa. 33:8), “And [Avraham] dwelt between Kadesh and Shur” (Gen. 20:1). He regards not man (Isa. 33:8) — has Avraham no merit in his favor? This is surprising! And who says that this verse does not refer to the angels? — Here it says, “Upon (MI-MA’AL) the wood”, while in another passage it says, “above (mi-ma’al) Him stood the seraphim” (Isa. 6:2).