Er & Onan’s Deaths and Reasons: Early Jewish Exegetical Approaches to Genesis 38:7-10

In 2005, I composed the following essay, which has sat proverbially collecting dust amongst my digital files. I hereby present the essay in its unadulterated form from 2005:

The early verses of chapter 38 of the book of Genesis, which relate the story of Judah’s sons and their downfall are somewhat unclear.  While there is some clarity regarding what they did, it seems like a rather simple explanation on the face of the text.  That is, it seems that Er did nothing in particular which the text mentions in which it states that “he was evil in God’s eyes” (Gen. 38:7), perhaps being an anagrammatic switching of the consonants in his name.[1]  As for Onan, the reason for his death was not due to coitus interruptus, and certainly not due to masturbation, but rather due to his not raising up seed for his brother.[2]  What was it that he did that was “wicked in the eyes of the Lord” (Gen. 38:10)?  It was “whenever he would come on to his brother’s wife, that he would destroy, towards the ground, so that he would not be giving seed for his brother” (Gen. 38:9), as he knew “that the seed would not be his” (Gen. 38:9).   Worse, as this chapter focuses on the formation of the tribe of Judah,[3] Onan’s crime is transformed into an egregious interruption to this collective project.  For those interested, however, in trying to derive an ethic from the text are wont to ask what it was that Er and Onan did that one ought to avoid.  Although the focus in this paper will be on Philo and the Rabbis, the books of Chronicles and Jubilees also approach this text with their own perspectives.


Inner-Biblical Exegesis – Chronicles[4]

The extent of Chronicles’ approach to what these brothers did is limited to 1 Chronicles 2:3b: “And Er, the first-born of Judah, was evil in the eyes of God, and he killed him.”  While the author of Chronicles copied Genesis quite nearly verbatim in relating the fate of Er, he very obviously omitted the action and fate of Onan.  Therefore, it would seem that according to the author of Chronicles, the evil of Er was incredibly so that it was worthy of mention.  This is perhaps due to his being “so persistent in his evil that [God] slew him.”[5]  However, for Onan, the author did not see enough reason to mention any wrongdoing on his behalf.  This lack of attribution of any malfeasance on Onan’s behalf shows that the author of Chronicles saw Onan as having done nothing noticeably bad.  Thus, while the Chronicler may have read Genesis, and understood that Onan had done evil, it was not significant enough for him to mention.


Deuterocanonical Exegesis – Jubilees[6]

The author of Jubilees sees the actions of Er and Onan more clearly than does the author of Chronicles.  While he writes the same as the Chronicler in 41:3, he gives a little back story to Er’s evilness.  In 41:2a, he writes that Er “hated (her) and would not lie with her because his mother was from the daughters of Canaan.”[7]  Thus, the evilness of Er, to the author of Jubilees, is somehow related to his not consummating his marriage with Tamar, rather than some sort of abstract, ongoing evilness.

The author of Jubilees reworks the story in Genesis in order to highlight how he viewed the cause of Onan’s death.  Contrasted against Genesis’ portrayal of Onan frequently spilling his seed (38:9), the author of Jubilees understands it as happening the very first time he got together with Tamar (41:5): “And ‘Onan knew that the seed would not be his (but) only his brother’s and he entered the house of his brother’s wife and poured out (his) seed on the ground and he was evil in the sight of the Lord and he killed him.”[8]  Thus, he sees it as a direct consequence of spilling out his seed (albeit, just as in Genesis, still motivated by selfishness), rather than a more protracted occurrence of seed-spilling.

The author of Jubilees portrays both brothers as having not procreated with Tamar: Er did not even lie down with her, while Onan refused to give his seed for his brother to her.  The author of Jubilees understood Onan being perceived as evil in the sight of the Lord due to his spilling of his seed out on the ground more so than not giving Tamar seed.


Philo’s Understanding

Philo understood the actions allegorically, which is not surprising considering that this is his usual approach – nay, main concern.[9]  As such, it stands out among the others presented here as he is the only one to deal with the story in an allegorical fashion.  Firstly, he considers Er in terms of what his name means, that of “leather” – a play on his name by switching the vowelization of his name, that instead of a zere between the ‘ayin and the resh, there is a holem.  What is problematic, for Philo, is that being this “leather” represents being “an evil thing, and one which plots against the soul, and which is at all times lifeless and dead.”[10]  Philo views that innate evilness as being the crux of the reason to God’s slaying of Er, as he says that God killed him “without any apparent cause for this judgment of his character,”[11] and similarly, “without any cause being alleged.”[12]  So, unlike the author of Jubilees, his approach did not see Er as doing anything particularly evil, but rather embodying evil, if by nothing else, then solely by his name.

Philo’s view of Onan was that he was selfish; not giving his seed in his brother’s name, and failing to fulfill the action of levirate marriage.  Moreover, what he did wrong, in the eyes of Philo, was that he “transgressed all the boundaries of self-love and of fondness for pleasure.”[13]  Philo states that these sort of selfish actions cause an “overturning and throwing into confusion of [societal mores], sowing seed for [himself] alone, and nursing up pleasure, that gluttonous intemperate origin of all evil.”[14]

Philo’s view of the action of Onan, then, is that it was representative of a selfishness that was harmful to his family and possibly to society at large.  Inasmuch as Gaca has shown that Philo is procreationist,[15] it is striking that Philo attacks neither Er nor Onan for not providing seed for Tamar, per se.  Specifically, “Philo maintains that human sexual activity should be motivated only by the purpose of procreation, that reproductive sexual relations should occur within the marriage bond (my emphasis – DK), and that all other sexual relations are overly hedonistic and hence blameworthy.”[16]  Thus, for Philo, Er died due to his innate wickedness and Onan due to his wicked selfishness.


Rabbinic Understanding

The only tannaitic text which mentions Er and Onan speaks of them as having done similarly, and not only that, but in a fashion which is not to be emulated: “All twenty-four months (that a month is nursing a child), he threshes on the inside and winnows on the outside, the words of Rabbi Eliezer.  [The Sages] said to him, ‘Such resembles none other than the practice of Er and Onan.’”[17]  Thus, already by the time of the Tannaim, the actions of Er and Onan were already understood as being the same –  that of coitus interruptus.[18]  However, the exegetical basis for this understanding of their actions was not mentioned until the time of the Amoraim.  It is the fourth-century Babylonian sage, Rav Nahman, son of Isaac, who explains the exegetical equating of their actions, by taking the language of Genesis 38:10 of “and He slew him also,” as understanding the “also” as being from the same action, that of also spilling his seed.[19]  Additionally, a midrash pins the wickedness of Er to another specific act – that of unnaturally cohabiting.[20]

The rabbis not only accused Er and Onan as having committed a wrong, but investigated their motives: for Onan, they quote Gen. 38:9, which is explicit, but they had to figure out a reason for Er, as the Biblical text gives none.  They said that Er did so (spill his seed) in order that Tamar would not conceive, which would have resulted in her diminishing her beauty.[21]

Similar to Philo, the rabbis conceived of homiletical plays on the names of the brothers: Er being called so, as he was destroyed from the world,[22] and Onan, as he brought grief upon himself.[23]  +yes, I know I need to show the etymology of these+

In a homiletical vein, early Amoraim articulated warnings against what they perceived to have been the practices of Er and Onan.  Since thy received an understanding of the sins from the Tannaim,[24] they understood the errorfulness of committing such an act, and were compelled to establish punitive measures – albeit from heaven and not from man.  The third-century sage, Rabbi Yohanan, declared that anybody who emits semen in vain deserves death, directly quoting Gen. 38:9-10.[25]  However, a few of his contemporaries (Rabbi Yizhak, Rabbi Ammi, and Rav Assi) argue on him, citing other verses (Is. 57:5 and Deut. 12:2), making plays on the verses and making comparisons to other severe sins (those of murder and idol worship – two of the three most severe sins).[26]  A contemporary of Rabbi Yohanan’s, Rabbi Ammi, who argues with him on the last point, nevertheless sees the wickedness of Er as being particularly bad, in that he cites the text in Genesis that describes Er as evil in order to derive that “Anyone who brings himself to coming to sexual thoughts is not entered into the chamber of the Holy One, blessed be He.”[27]



Due to the semi-ambiguity of the verses in Genesis 38:7-10 as to the causes of the deaths of Er and Onan, various views have arisen in early Jewish understandings of this text.  Chronicles sees the life of Er as wicked, exactly as Genesis portrays him, while implicitly seeing nothing wrong with Onan’s actions.  The author of Jubilees reworks the fabula in Genesis such that Er did not like his wife, nor did he even try to procreate with her.  Further, they posit a direct causal connection between Onan’s seed-spilling as soon as he approached Tamar and his subsequent death.  Philo sees no inherent wrong in the seed-spilling, but rather takes issue with Onan’s selfishness and Er’s innate wickedness.  The Rabbis, and the rest of Judaic tradition to follow,[28] understood the two brothers’ actions to be identical – as that of destroying the seed via coitus interruptus and not providing seed for Tamar, and thus hermeneutically transforming such action into a Biblical proscription.


[1] Nahum M. Sarna, The JPS Torah Commentary: Genesis, ed. Nahum M. Sarna (Philadelphia: The Jewish Publication Society, 1989), p. 266, n. 7, s.v. displeasing.

[2] Leonard Mars, “What Was Onan’s Crime?”, Comparative Studies in Society and History 26, no. 3 (1984), 435.

[3] Pierre Grelot, “Le Péché de Ônān (Gn., XXXVIII, 9),” Vetus Testamentum 49, no. 2 (April 1999), p. 145.

[4] Although Er and Onan are brought up also in Genesis 46:12 and Numbers 26:19, their mentions are brought up in those places as merely part of the genealogical listing, and merely state that they had died in Canaan, not seeing fit to bring up any reasons for their deaths.  Thus, Chronicles is the only other time in the Bible where they are brought up beyond merely a genealogical listing.

[5] Jacob M. Myers, I Chronicles, The Anchor Bible 12 (Garden City, NY: Doubleday & Company, Inc., 1965), p. 13.

[6] Although Pseudo-Philo mentions Er and Onan in his Biblical Antiquities 8.11, it is, like Genesis 46:12 and Numbers 26:19, in simply a genealogical context and not to discuss their deaths.  Thus, Jubilees is the central text in the deuterocanon which discusses the deaths of Er and Onan.

[7] O. S. Wintermute, trans., “Jubilees,” The Old Testament Pseudepigrapha, vol. 2, ed. James H. Charlesworth (New York: Doubleday, 1985), p. 130.

[8] Ibid.

[9] Yehoshua Amir, “Philo and the Bible,” Studia Philonica 2 (1973), 7: “…it is the allegorical interpretation which is Philo’s main concern.  That is because he sees the Torah not merely as a code of law for living in the world, but as an allegorical expression of the truth about God and the soul’s relationship to him.”

[10] “Allegorical Interpretation, III,” in The Works of Philo: Complete and Unabridged, trans. C.D. Yonge (Peabody, MA: Hendrickson Publishers, 2004), p. 57.

[11] Ibid.

[12] Ibid., p. 58.

[13] “The Posterity and Exile of Cain,” in The Works of Philo: Complete and Unabridged, trans. C.D. Yonge (Peabody, MA: Hendrickson Publishers, 2004), p. 150.

[14] Ibid.

[15] Kathy L. Gaca, “Philo’s Principles of Sexual Conduct and Their Influence on Christian Platonist Sexual Principles,” The Studia Philonica Annual 8 (1996): 21-39.

[16] Ibid., p. 22.  It is interesting to note further that this “procreationist priniciple is foreign to and incompatible with the thought of the rabbinic tradition” (Ibid., p. 27, n. 22).

[17] Yevamot 34b.


[19] Ibid.

[20] Genesis Rabbah 85:4.

[21] Yevamot 34b.

[22] For an explanation of this, see Mars: “What Onan did was to exterminate Er, to erase his name from the world of the living.  Undoubtedly, Er was physically dead but by means of the Levirate his name could have been perpetuated; he could have given life by the magnanimous and altruistic act of a dutiful brother…” (436).

[23] Genesis Rabbah 85:4.

[24] See note 15.

[25] Niddah 13a.

[26] Ibid.  For more on the severity of these sins, see Tosefta Peah 1:2, where the only missing of the three most severe commandments is sexual immorality, which may be hinted at here.

[27] Niddah 13b.

[28] See, for instance, Rashi, Gen. 38:7, s.v. Ra’ be’ene hashem, as well as Rambam, Hil. Iss. Biah 21:18 and Shulhan Arukh, Even haEzer 23:1-2

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