Midrasch zu Schemot 32:5

(Fol. 6b) R. Eliezer, the son of R. Jose the Galilean, says: "A court is forbidden to attempt an arbitration, and the [judge] that makes settlements commits a crime; and he who praises the mediators despises the law, as it is said (Ps. 10, 3) The robber blesseth himself when he hath despised the Lord, but let the law cut through the mountain (justice under all circumstances), as it is said (Deut. 1, 17) The judgment belongs to God." And so said Moses our master: "Let the law cut through the mountain." But Aaron [his brother] loved peace, ran after it, and used to make peace between a man and his associate, as it is said (Mal. 2, 6) The law of truth was in his mouth, and falsehood was not found on his lips, in peace equity he walked with Me, and many did he turn away from iniquity. R. Eliezer says: "If one had stolen a saah of wheat and had ground, kneaded and baked it, and separated the heave (Challa) of it, how can he recite a benediction over it? For not only is it not a benediction, but it is rather a blasphemy! Concerning this, the passage reads (Ps. 10, 3) The robber blesses … . despises the Lord." R. Maier says: "The passage, the robber, etc., refers only to Juda, for it is said (Gen. 37, 26) And Judah said unto his brothers, 'What profit (betza) will it be if we slay our brother?' And whoever praises Juda [for his advice] despises the Lord; and concerning him is said: He who blesses Botzea despises the Lord." But R. Joshua b. Karcha said: "On the contrary arbitration is a meritorious act, as it is said (Zech. 8, 16) With truth and the judgment of peace, judge ye in your gates. How is this to be understood? Usually, where there is judgment, there is no peace; and where there is peace, there is no judgment. It must then refer to arbitration, which brings peace. The same must be explained about David, concerning whom it is said (II Sam. 8, 16) And David did what was just and charitable unto all his people. How can these five terms be reconciled? For a thing that is just is not charitable, and if charitable then it is not just. We must therefore say that it refers to arbitration, which contains both." The first Tanna, however, [who said above that arbitration is prohibited], explains the passage thus: He, (David), judged in accordance with the strict law — he acquitted him who was right and held him responsible who was guilty, according to the Law; but when he saw that the loser was poor and could not pay, he used to pay from his own pocket. Hence he did justice to one and charity to the other. Rabbi, however, pointed out the following difficulty, it is written. Unto all his people, and according to the above explanation, it ought to be to the poor. Therefore, said Rabbi: "Although he did not pay from his pocket, it was nevertheless counted as justice and charity; justice to the one, for having returned his money; and charity to the other, for delivering the theft out of his hand." (Fol. 7) All the Tannaim mentioned above differ with R. Tanchum b. Chanilai, who said: "The above-cited verse (Ps. 10) was quoted in reference to the golden calf, of which it is said (Ex. 32, 5) And when Aaron saw this. What did he see? R. Benjamin b. Jepheth said in the name of R. Elazar: 'He saw Chur, who was lying killed before him.' And he thought: 'if I do not listen to them, they will do likewise unto me, and will bring about such a condition as is said (Lam. 2, 20) Shall there be slain in the sanctuary of the Lord the priest and the prophet; for which there shall never be a remedy. It is better for them that I should make the golden calf, and for that probably there will be a remedy by repenting.'" [Hence the above passage].

Rabbi Berachiyah said in the name of Rabbi Abbah Bar Kahana expounding on the verse about Aaron. At the time when the Israelites were about to commit the act [make the golden calf] they first came to Chur, and they said to him: "Make us a god!" Since he did not listen to them, they rose up and slew him. This is why it's later written in the prophets: "Also in your wings we find the blood of the souls of the innocent and the poor etc." This refers to the blood of Chur. . . . " Afterwards, they went to Aaron and said to him: "Make us a god." Aaaron had heard about what they did to Chur, and became afraid. It is therefore written: "Aaron was frightened and built an alter before them." Aaron was frightened that he might be the one who was going to be slaughtered. Aaron said, what should I do? They've already killed Chur, and he was was a prophet. Now if they kill me, the priest, they will fulfill the word later written in scripture: "Should priest and prophet be slain in the sanctuary of YHWH (Eicha 2:20)." If they kill me, they will all be exiled. Here is another interpretation (Davar Acher): Aaron saw this, and built an altar before it (Exodus 32:5). What did he see? He saw the situation playing out like this: If they build it, one will bring a pebble, another a larger stone, and they will finish the building of the idol in one day. If I build it, then I can delay and dally, and give time for our teacher Moses to come down the mountain and then destroy this idol worship. And if I build it, I can dedicate it to the name of the Holy one Blessed be God, therefore it is written: "Aaron called and said this shall be a festival for YHWH." It is not written a feast for the calf, but a feast to YHWH. Another interpretation: "And Aaron saw this, etc." What did he see? He saw the situation playing out as follows: "If they build it the sin will be upon them, but if it will be better if I build it, so that the sin should be upon me and not the people. Rabbi Abba Bar Yodan said in the name of Abbah, we can give a parable that demonstrates this. It's like the son of a king who became filled with pride in his heart and took a sword and rose up to try and cut his father. The son's tutor said to him: Don't trouble yourself, leave it to me and i'll do cut him for you." The king saw the tutor and said to him: "I know what your intention was, it was that you believed it better that the sin should be upon you than upon my son. As you live, you shall not leave my palace, and that which remains over from my table, you shall eat it, and you will receive twenty four perks. So too with Aaron: "You shall not leave my palace" is compared to "He shall not go out of the sanctuary Leviticus 21:12"And that which remains of the table, you shall eat it" is compared to: "That which is let of the meal-offering shall be Aaron's and his sons (Leviticus 2:3)." The twenty four perks is paralleled to the twenty four gifts of the priesthood assigned to Aaron and his sons. . . .

Why did He elevate Aaron and his sons to that holy station? R. Mani of Shaab and R. Joshua of Sikhnin said in the name of R. Levi: When the Israelites pleaded with him to erect the golden calf, they said to Aaron: Up, make us a god (Exod. 32:1). Thereupon Hur the son of Caleb arose and rebuked them. They attacked him and killed him. Aaron beheld what had happened and feared (vayir’a) for his own life, as it is said: And when Aaron saw (vaya’r) he built an altar before it (ibid., v. 5). You know that they killed Hur, for Moses told them before he ascended the mountain: Behold, Aaron and Hur are with you; whosoever hath a cause, let him come near unto them (ibid. 24:14), but after he descended, you find that he did not refer to Hur either as living or as dead. What does Scripture say: And Moses said to Aaron: “What did this people unto thee, that thou hast brought a great sin upon them?” (ibid. 32:21). Obviously they must have killed Hur.