Regarding the subject of Yibum (Levirate marriage), what is the source, if any, that this is also an obligation on a Noahide?

Many of the discussions on this Q&A site concerning Yibum connect to the discussion of Yehuda and Tamar. But the Lubavitcher Rebbe citing the Rogatchover Gaon in connection with the subject of the laws associated with a "Rebellious City" makes clear that the Avot were not obligated in the 613 commandments, meaning they were not commanded to observe them. Their fulfillment of the 613 commandments of the Torah was voluntary.

One of the consequences of this distinction which the Rebbe explains was that their observing of the 613 commandments could not be in conflict with those prohibitory laws which were obligatory upon a Noahide at that time.

The prohibitions relating to marriages of consanguinity are generally obligations that do fall upon a Noahide in the sources that I have seen. But since Yibum appears to override that prohibition, I am speculating that perhaps Yibum is also obligatory upon a Noahide.

Please explain any reasoning carefully and cite all sources clearly and completely in any responses posted. And thanks to all for your input.

  • 3
    Which blog? Can you link to them? I see no reason think Noahides are commanded in Yibbum. Are you sure "marriages of consanguinity" are still prohibited to Noahides after the consanguinity is lost (ie. divorce/widow)? What about the prohibition on marrying your wife's sister?
    – Double AA
    Dec 17, 2014 at 16:50
  • @DoubleAA I assume he was referring to MY as a blog. Dec 17, 2014 at 18:30
  • 3
    @YeZ That would be unfortunate. Yaacov please see our tour to better understand what this site is.
    – Double AA
    Dec 17, 2014 at 18:34
  • @DoubleAA I actually have to question my theory, because he refers to "many discussions" on "this blog" and our site only has one such discussion, as far as I have found in a brief search. Dec 17, 2014 at 19:02
  • 1
    I searched a couple of keywords on Mi Yodeya. The subject came up across several topics. Dec 17, 2014 at 20:48

2 Answers 2


There is a dispute of the Rishonim as to whether or not daughter in law is a relationship prohibited to Noahides (Ramban vs. Rashba). The Ramban (to Yevamos 98a) holds that Noahides have no prohibition of relationships with relatives who are not blood relatives. He brings a proof to this from the fact that Yehuda absolved Tamar upon discovering her identity, and she was not put to death for violating the prohibition of Father-in-Law/daughter-in-law. Yibbum, he writes, was a minhag, and therefore Yehuda did not remain with Tamar, but there was no mitzvah which could have overridden the prohibition if it would have existed. (The Ramban to Bereishis 38:2 explains that there is some mystical benefit that is inherent in Yibbum, and therefore the wise men of the ages practiced Yibbum even though there was no formalized Mitzvah.)

The Rashba (same place) on the other hand, holds that this is not a proof, and writes that even if Noahides had a prohibition to relatives through marriage, the mitzvah of Yibbum would have overridden it. The Rashba explains that before Matan Torah, Yibbum extended to all relatives, and that Mitzvah overrode the prohibition of relationships with relatives.

Rashba Yevamos 98a s.v. Ger:

ותדע לך שהרי יהודה אמר על כלתו צדקה ממני, ואלו היתה אסורה לו משום כלה, אכתי חייבת מיתה היא משום ערוה לכולי עלמא, דהא בית דין של ישראל ממיתין עליה, אלא ודאי עריות דאישות דקרובים לית להו. ומיהו אין תמר ראיה דמותרת היתה לו ליהודה דבר תורה משום יבמה, דקודם התורה היה יבום מותר בקרובין, אלא שרצה יהודה לנהוג בה כדרך שצותה התורה באחים, לא באב שהאח עיקר, ובקי היה בענינו.

Even the Rashba, however, identifies that this was only before the Torah was given.

When the Torah was given, it restricted the Mitzvah to the case in which it has the greatest effect, which is the case of a brother, who shares the closest genetic relationship (both parents are the same). In this case, it overrides (or precludes) the prohibition of brother's wife, but in all other cases, the prohibition supersedes whatever spiritual inherent benefit there may be. The inherent benefit still exists, however, and therefore the Rashba writes that when there is no prohibition in the way, such as in the case of Boaz, Yibbum is still a value. (This last paragraph is based on the shiurim of R' Tzvi Berkowitz.)

  • @Y ez Could you please provide links to your textual citations for both Ramban and Rashba. Or short of that, insert actual quotations of the language they use. In the case of Ramban, that may be difficult so a link might be better. Jun 27, 2017 at 13:40
  • @YaacovDeane I found the Rashba, can't find the Ramban online. Don't have access to Otzar HaChochma. Jan 19, 2018 at 4:10

Rambam Ch. 9 of Kings & Wars lists all prohibited relatives for Noahides, and "sister-in-law" is not on the list. Therefore, Yibum is not overriding any prohibition for them. Mr. Noahide, you want to marry your brother's ex-wife? That's totally your choice (well, you have to ask her first), whether there were kids or weren't; whether the marriage ended in death or divorce.

There had been a Yibum-like practice prior to Sinai; and it's possible that for the patriarchs trying to keep the 613, Yibum or quasi-Yibum may have overridden some of those. But for Noahides today? Zero mention of any of this.

  • Thanks Shalom. I'm familiar with the list from Rambam but that is not necessarily what the world follows. I would be very interested in whatever sources you can point to for the "Yibum-like" practice. Dec 17, 2014 at 17:34
  • Also, you may be interested in what follows. It is a portion of the discussion concerning incest from the Noahide Nations blog. They bring from Encyclopedia Talmudica, volume 4, pp.367-370 groups.yahoo.com/neo/groups/NoahideNations/conversations/topics/… Dec 17, 2014 at 17:37
  • @YaacovDeane Until you cite any other opinion, this seems like a good answer.
    – Double AA
    Dec 17, 2014 at 18:34
  • @YaacovDeane look at the Yehuda and Tamar story -- but unlike halachic yibum, the father could serve in the brother's stead. So there was a quasi-yibum practice in place at the time. (Lord Sacks comments something like: "one form of that custom became codified as halacha at Sinai.") Entire books have been written on what the Jews kept pre-Sinai. But we find N-O-W-H-E-R-E that a Noahide post-Sinai is obligated to marry his childless brother's widow, nor that he is prohibited from marrying his brother's ex-wife in other circumstances.
    – Shalom
    Dec 17, 2014 at 19:23
  • @YaacovDeane if a Noahide today asked if marrying his childless brother's widow would be a nice thing, I'd say maybe, depending on a whole host of human factors. But not a "mitzva per se." (There's a very odd Maharsha that Ploni Almoni thought that the value of quasi-yibum-via-cousin would override the prohibition of a marrying a Moabite woman -- but that's post-Sinai.)
    – Shalom
    Dec 17, 2014 at 19:25

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