Avraham Avinu enters the biblical narrative at the end of Parashat Noach. The details in this brief section are limited: We are told only that Avraham (who is married to Sarah and does not yet have children) is one of the three sons of Terach, who decided to relocate his family from Ur Casdim to Kena’an but instead settled in Charan. Immediately following this, at the beginning of Parashat Lech Lecha, God speaks directly to Avraham, ordering him to travel from Charan to an unnamed land where he will receive great reward. The Torah is silent on why God specifically chose Avraham to complete this mission and be the progenitor of a “great nation.”
There is clearly a need for some sort of backstory explaining Avraham Avinu’s life in Ur Casdim and his selection by God, and Chazal filled this void by creating the now-famous Midrash concerning Avraham and his father’s idols. The Midrash, which appears most comprehensively in BeReishit Rabbah (38:13), reads as follows:
Terach was a worshipper of idols. One time he had to travel, and he left Avraham in charge of his store … A woman entered carrying a dish full of flour. She said to [Avraham], “Offer it before [the idols].” Avraham took a club, broke all the idols, and placed the club in the hands of the tallest idol. When his father returned, he asked, “Who did all of this?” Avraham replied: “What have I to hide from you? A woman came carrying a dish of flour and told me to offer it before [the idols]. I did, and one of them said ‘I will eat it first,’ and another said ‘I will eat it first.’ The tallest one rose, took a club, and smashed the rest of them.” Terach said: “What, do you think you can fool me? They aren’t capable of thought!” Avraham said, “Do your ears hear what your mouth is saying?” Terach took Avraham and delivered him to [King] Nimrod. He said [to Avraham], “Let us worship the fire.” Avraham said to him, “Let us worship water, for it extinguishes fire.” Nimrod agreed, “Let us worship water.” Avraham continued, “If so, let us worship the clouds, which provide water.” … Nimrod replied: “Your words are meaningless—I only worship fire. I will throw you into it, and the God you worship can save you from it.” [Avraham’s brother] Haran was hidden and considered his options, saying [to himself], “If Avraham is victorious, I will say I am with Avraham, and if Nimrod is victorious, I will say I am with Nimrod.” When Avraham was thrown into the fiery furnace and saved, they asked [Haran], “With whom are you?” He replied, “I am with Avraham.” They took him and threw him into the fire, and his insides burned up and he died before his father Terach, as it says, “Haran died in the face of his father Terach” (BeReishit 11:28).
This Midrash is multifaceted and contains the following seven elements:
1) Terach is a worshipper of idols.
2) Avraham rejects Avodah Zarah by destroying his father’s idols and ridiculing Avodah Zarah in front of both Terach and Nimrod.
3) Nimrod is king.
4) Nimrod worships fire.
5) Nimrod throws Avraham into a fiery furnace for his religious beliefs.
6) Avraham is saved from the furnace by a miracle of God.
7) Haran dies in the conflict.
Only elements 1 and 3 appear explicitly in Tanach. Yehoshua begins his farewell address to Bnei Yisrael by recounting their origins: “Beyond the river your ancestors always dwelled—Terach, the father of Avraham and Nachor—and they served other gods. But I took your father Avraham from beyond the river and led him all the way across the land of Kena’an” (Yehoshua 24:2-3). This Pasuk, in fact, is quoted in the Haggadah to prove that our ancestors were initially idol worshippers, but that beginning with Avraham Avinu, they served God. As for element 3, the Torah records earlier in Parashat Noach that Nimrod was a “mighty hunter” whose kingdom encompassed much of Mesopotamia (BeReishit 10:8-10). Chazal assume that Ur Casdim was located in Nimrod’s domain, so Terach and Avraham were subject to Nimrod’s authority.
The other elements of the Midrash, however, are not explicit and must be inferred from the text. Elements 5 and 6 emerge from the unusual phraseology of a Pasuk in Lech Lecha and a parallel story in Sefer Daniel. Immediately before the Brit Bein HaBetarim, God assures Avraham that his descendants will inherit Kena’an, saying, “I am Hashem who took you out (“Hotzeiticha”) from Ur Casdim to give you this land as an inheritance” (BeReishit 15:7). As Ramban notes, the word “Hotzeiticha” connotes a miracle (as opposed to the more mundane “Lekachticha”); the same word is used by God at Har Sinai to describe His taking Bnei Yisrael out of Egypt (Shemot 20:2), which, of course, involved many miracles. And what was the miracle performed for Avraham? Chazal interpreted the Pasuk in Lech Lecha to mean that God performed a miracle and took Avraham out of the “fire of Casdim,” since the word “Ur” can mean fire (e.g. Yechezkel 5:2, which reads, “Shelishit BaUr Tav’ir,” “burn one third in an Ur.” Clearly, “Ur” means fire in this context). But the notion that Avraham was saved specifically from a furnace is borrowed from Sefer Daniel (Daniel 3:1-30). Chananyah, Misha’eil, and Azaryah were three young men who had been taken from Eretz Yisrael to Bavel (Babylon) and were selected as advisers to King Nevuchadnetzar. When the three advisers refused to bow to a golden statue Nevuchadnetzar had erected, the king ordered for them to be tied up and thrown into a fiery furnace. Yet the fire had no effect on the trio; even their clothing did not smell like fire (Daniel 3:27). Both the three advisers and Avraham refused to perform Avodah Zarah in the face of a mighty king, and Chazal deepened the connection by having Avraham also thrown into a fiery furnace as a punishment for defying Avodah Zarah. Thus, God tells Avraham, “I am Hashem who took you out from the fiery furnace of Casdim.”
Element 4, Nimrod’s worship of fire, is more complicated. The Gemara (Eiruvin 53a) attributes the name “Nimrod” to the fact that Nimrod caused the world to rebel against God’s reign (“Nimrod” contains the root “Mem, Reish, Dalet,” meaning “to rebel”). Rashi explains that Nimrod advised the Dor HaPelagah to build Migdal Bavel in order to challenge God’s authority. Performing Avodah Zarah is also a direct challenge to God’s authority, and would therefore likely be practiced by Nimrod. Chazal then had Nimrod worship fire in the Midrash in order to set up a showdown between Nimrod’s god and Hashem: Would the fire consume Avraham, or would Avraham survive? When Avraham emerges unscathed from the fiery furnace, it is clear that Nimrod’s god is utterly false while only Hashem is true, thus validating Avraham’s belief.
Element 7, the death of Haran, is sourced at the end of the Midrash: The simple reading of the Pasuk “Haran died in the face of (“Al Penei”) his father Terach,” indicates that Haran died during the lifetime of his father, but it could also mean that he died as a result of his father. If Terach had not brought Avraham before Nimrod, Haran would have never been forced to choose between Avraham and Nimrod, and he would not have been killed.
Element 2, Avraham’s rejection of Avodah Zarah, must be true, for if not, what would distinguish him from Terach and his ancestors that would motivate God’s choosing him? But the methods by which Avraham rejects Avodah Zarah require further explanation. From where do Chazal derive that Avraham destroyed his father’s idols? Granted, Avraham must reject Avodah Zarah in the Midrash, but this should not compel Chazal to feel that Avraham must smash the idols. Additionally, Avraham’s use of pointed sarcasm that ridicules Avodah Zarah seemingly lacks a basis. No less than three times—explaining the destruction of the idols to his father and exposing the nonsensical nature of Avodah Zarah to both Terach and Nimrod—Avraham uses strong, sardonic language to convey his point. One might be tempted to attribute this aspect of the Midrash, as well as Avraham’s destruction of the idols, to the creativity Chazal often exercised in constructing a Midrash, but perhaps they drew these details from elsewhere.
Surprisingly, these details appear in Sefer Shofetim, in the account of Gidon’s rise to leadership (Shofetim 6:1-32). Following 40 years of peace, Midyan begins to oppress Bnei Yisrael, and Hashem selects Gidon to lead the resistance against Midyan. Hashem commands Gidon to destroy the Mizbei’ach to Ba’al belonging to his father, Yo’ash, and to cut down the nearby Asheirah tree. Gidon is then to build a Mizbei’ach to Hashem and offer a sacrifice using the wood from the Asheirah tree. The locals wish to kill Gidon upon their discovery that he destroyed the Avodah Zarah, but Yo’ash rises to his son’s defense, saying: “Do you have to fight for Ba’al? Do you have to vindicate him…If he is a god, let him fight his own battles, since it is his Mizbei’ach that has been torn down!” (Shoftim 6:31). Like Gidon, Avraham destroys his father’s idols, and in both accounts, sarcastic remarks are directed at the idolaters. Yes, it is Yo’ash, not Gidon, who utters this remark, but it serves exactly the same purpose as Avraham’s sarcasm: exposing the contradictory nature of Avodah Zarah, for the idolaters themselves do not believe in the power of their gods.
It was no accident that Chazal inserted two details found in the Gidon narrative into the Avraham backstory. Rav Amnon Bazak reasons that Chazal hinted at the story of Gidon in order to explain God’s selection of both Gidon and Avraham. God does not arbitrarily select the leaders of the Jewish people; rather, He chooses those who demonstrate unwavering faith and a sense of self-sacrifice. Both Avraham and Gidon were willing to destroy their fathers’ Avodah Zarah despite knowing the consequences, and only someone with such a commitment to Avodat Hashem can lead Bnei Yisrael. However, as Rav Bazak notes, there are three significant differences between the story of Gidon and the Midrash about Avraham:
1) Gidon is instructed by God to destroy the Avodah Zarah, while Avraham acts of his own accord.
2) Gidon “took ten men from among his servants … but since he was afraid to do it by day because of his father’s household and the people of his city, he did it at night” (Shoftim 6:27). Avraham does not show any fear in the Midrash.
3) Gidon’s father, Yo’ash, supports his son’s cause and speaks on his behalf, while it is Terach, Avraham’s father, who takes Avraham to Nimrod to be punished.
Gidon seems a bit uncomfortable in the role of leader, and I believe this accounts for his limited success in that position. Although he defeats Midyan and restores peace to Eretz Yisrael, Gidon is unable to maintain lasting order. Idol worship returns immediately upon his death; Bnei Yisrael, in fact, worship the very object Gidon fashioned into a memorial for the military victory over Midyan. Additionally, Gidon’s evil son, Avimelech, seizes power and institutes a reign of terror over Bnei Yisrael. Conversely, Avraham is bold and shows no fear in the Midrash—as befits a natural leader. Whereas Gidon, ironically, can be held responsible for increasing idolatry, Avraham is credited with increasing Avodat Hashem (see Rashi to BeReishit 12:5 s.v. VeEt HaNefesh Asher Asu BeCharan). Avraham’s work is not undone, as his son, Yitzchak, carries on his message and becomes the next leader of the Jewish people. But despite their differences, Chazal compared the two in order to express the idea that they were selected by God for the same reason—they asserted the authority of God by destroying Avodah Zarah.
One of the most well-known episodes of Avraham’s eventful life, the story of Avraham destroying his father’s idols and its aftermath, appears nowhere in the text. But through a close reading of various Pesukim and biblical stories, Chazal created a Midrash that convincingly details Avraham’s life in Ur Casdim and perfectly explains his selection by God.
 I use the collective “Chazal” to refer to those who contributed to the creation of this Midrash. Midrashim, especially those as elaborate as ours, usually do not have one single author; rather, they are often the accumulation of several ideas and develop over the course of many years.
 The consensus among modern day Bible scholars is that Ur Casdim was located in Southern Mesopotamia, as were the various regions listed in Parashat Noach as being part of Nimrod’s kingdom.
 One of the six uses in Tanach of “Ur” as a word for fire appears in Yeshayahu 31:9. The Pasuk reads, “Asher Lo Ur BeTzion VeTanur Lo BiYrushalayim,” “Who has a fire in Tziyon and a furnace in Yerushalayim” (the Pasuk refers to Hashem). The parallelism between “Ur,” fire, and “Tanur,” furnace, supports this element of the Midrash, since it indicates that the word “Ur” is synonymous with “furnace.” It is possible that Chazal were aware of this Pasuk when creating the Midrash and felt it confirmed the aforementioned reading of the Pasuk in Lech Lecha.