Genesis 38 says that instead of impregnating Tamar, Onan let his seed go to waste, and that this angered God, and therefore God killed Onan.

I have a vague memory of reading somewhere in the Talmud that there is a discussion to determine the exact reason for his death. The accepted reason was that his seed was wasted. Where exactly would this Gemara be? Or am I remembering something different?


1 Answer 1


Yevamot 34b explains it thus:

מיתיבי כל עשרים וארבעה חדש דש מבפנים וזורה מבחוץ דברי ר' אליעזר א"ל הללו אינו אלא כמעשה ער ואונן כמעשה ער ואונן ולא כמעשה ער ואונן כמעשה ער ואונן דכתיב והיה אם בא אל אשת אחיו ושחת ארצה ולא כמעשה ער ואונן דאילו התם שלא כדרכה והכא כדרכה בשלמא אונן דכתיב ביה ושחת ארצה

Soncino translation, my notes in braces:

An objection was raised: During all the twenty-four months {after a birth, when a mother is nursing} one may thresh within and winnow without {see below}; these are the words of R. Eliezer. The others said to him: Such actions are only like the practice of Er and Onan! -Like the practice of Er and Onan, and yet not [exactly] like the practice of Er and Onan: ‘Like the practice of Er and Onan’, for it is written in Scripture, And it came to pass, when he went in unto his brother's wife, that he spilt it on the ground; and ‘not [exactly] like the practice of Er and Onan’, for whereas there it was an unnatural act, here it is done in the natural way.

[The source for] Onan's [guilt] may well be traced, for it is written in Scripture, That he spilt it on the ground

From the footnotes in the Soncino translation: "thresh within and winnow without: Euphemism. This would prevent possible conception which might deprive the young child of the breast feeding of his mother."

Now, the reason Onan was spilling his seed on the ground is that he didn't want to father a child with Tamar (38:9). In other words, he performed yibum but then denied the purpose of yibum -- he sabotaged it to Er's and Tamar's detriment. It would have been better for him to refuse the marriage in that case. So we could say that he was punished for this. The sequence, in any case, is: decide not to fulfill the purpose of yibum -> spill his seed during the act -> punishment.

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    The reason Onan died is his lack of will to give his brother son trough Yebum, not wasting seed(That is how the gmara interpetes Yevamot in 34B, few lines after you stoped translating).
    – Alaychem
    Commented Jan 20, 2014 at 7:58
  • 2
    @Alaychem IINM the g'mara there gives לא לו יהיה הזרע as the reason for ושחת ארצה, and ושחת ארצה as the reason for his death — but not לא לו יהיה הזרע as the reason for his death. Maybe I'm reading it wrong, though.
    – msh210
    Commented Jan 20, 2014 at 8:45
  • @msh210 I do understand what you say,but I think that if you were right there was no diffrence between the brothers(both died because "ושיחת ארצה") but the gemara stats othrwise
    – Alaychem
    Commented Jan 20, 2014 at 18:19
  • @msh210 More specifically, sleeping with your brother's wife is, by definition, a violation of adultery. There is a specific heter through the process of Yibum, which allows the issur for the kum aseh of lehakim shem le'achiv. Onan, by refusing to fulfill the aseh, had no heter and therefore was violating gilui arayos! Commented Dec 22, 2016 at 12:37

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