An answer on this question suggests that if a boy fathers a child before he is bar mitzvah (which is physically possible), then he fulfills p'ru ur'vu even though he wasn't yet commanded. Is that a general principle? I am particularly asking about the "once in your life" mitzvot, not the things you do regularly so there will be plenty more opportunities later.

Suppose a minor writes a sefer torah (by donating money he earned to help pay for one), and this is the only time in his life that he does so. Or, suppose that minor fathers two children before bar mitzvah and no more. Are these people yotzei? Does an action performed before you were obligated filfill what you will later be obligated in?

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    If the answer turns out to be "yes, he's yotzei", then I may have a followup question about geirim that I'll ask separately. Commented Dec 9, 2013 at 15:49
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    This is likely a case-by-case situation depending if the obligation is to perform the action or have the result accomplished.
    – Double AA
    Commented Dec 9, 2013 at 16:37
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    @DoubleAA what are examples of "have the result accomplished" mitzvot? I think of mitzvot as things you need to do (or not do), not states you need to end up in, but maybe I'm missing something obvious. Commented Dec 9, 2013 at 16:40
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    I can't think of a good undebated example off hand, but we can ask it about nearly every mitzva. If I eat and am satiated then vomit, must I still bentch? Alternatively, if I eat some bread, bentch, and then eat a small amount of some more food so that now I'm satiated, must I bentch again? Pru urvu would seem to be an excellent case to ask this. Does the man fulfill his obligation if he was drunk/sleeping/insane when the child was conceived? Alternatively, what if he has a child but it dies?
    – Double AA
    Commented Dec 9, 2013 at 17:46
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    @DoubleAA thanks for your comments. I'm trying to ask the general philosophy question, and specifically about being obligated in mitzvot in general, versus the more situational cases like whether you're hungry or whatever. If someone who is not yet obligated because he's not technically commanded yet does something, does it count for him? If the rule is "that depends" then that could be an answer (especially if it depends on particular factors). If you can think of a better way to phrase the question, I'd welcome the help. Commented Dec 9, 2013 at 20:00

1 Answer 1


The Ragatchover writes [citation needed] that a positive Mitzvah can have three aspects to it.

  • The obligation to do it.
  • The continued fulfillment of it
  • The prohibition of stopping it

Most Mitzvos have one or two of those aspects, but Circumcision has all three, which we can see from the following examples

  • Someone born circumcised has to have a drop of blood taken. This fulfills the obligation "to do it."
  • There is a Medrash which says that Dovid HaMelech was standing in the bathhouse [unclothed] and he thought to himself that he has no Mitzvos, then he remembered that he has his Bris, and this comforted him. So just having it is itself part of the Mitzvah
  • It is forbidden to have surgery to make it cosmetically look like the circumcision never happened.

That is what I remember from the Ragatchover. The rest of this answer is my own association.

Other Mitzvos can be different. For example, with Lulav, before saying the blessing, the Esrog is left on the table or held upside down so that one does not fulfill the obligation before being able to say the blessing. Once the Lulav is held properly, the blessing can no longer be said, because it really only has the aspect #1, not #2.

Succah, by contrast, the Halacha is that if someone forgot to say the blessing before eating a meal and remembers after he is finished, but still sitting in the Succah, he can say a blessing at that point, because Succah has aspect #2. However, it lacks aspect #3 - there is no prohibition in leaving the Succah afterwards. [The first night of Succos has #1 for sure, I don't know if the rest of the time does or not].

With p'ru ur'vu it lacks #1 (in other words attempts to fulfill it more constitute a Hechser Mitzvah - preparation for a Mitzvah), therefore children conceived before Bar Mitzvah still count. As the Lubavitcher Rebbe once said, it is a Mitzvah you can choose not to do, but it is not a Mitzvah you can choose to do. With regards to a Ger, this is a Machlokes, but it could be that this a question of if the children have to be related to the person or not, rather than a question of if the Mitzvah has an aspect of #1. Arguably it also has #3, in that if someone's children cannot themselves have children or they die before having children, the Mitzvah is unfulfilled, but it is hard to make a practical example of #3 in this case. Perhaps you could bring the fact that castration is forbidden as evidence for #3 in this case.

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