At what halachic time does a boy having his bar mitzvah become chayav b'mitzvot? It seems to me that the most likely times are either shkia or tzeit.

  • 1
    Would you agree that during Bein haShemashot he is a Safek? How is this different than any other "when does day end and night begin" sort of question (eg. date of Brit Milah, start of Shabbat, etc.)
    – Double AA
    Commented May 26, 2015 at 21:00
  • It certainly might be analogous to Brit milah, an argument of which i wasn't aware. As for Shabbat, i know that we're stricter about that than other things.
    – Scimonster
    Commented May 26, 2015 at 21:06
  • Presumably since we are lenient with rabbinic mitzvahs and strict with torah ones, perhaps it depends what he wants to do. I.e. If he wants to say kiddush for everyone, would probably need to rule strictly and wait until dark. Something rabbinic, can be lenient and wait until shkiya...
    – andrewmh20
    Commented May 26, 2015 at 22:30
  • 1
    Perhaps during Bein Hashmashos he is not yet Mechuyav since he doesn't yet have the חזקה שהביא שתי שערות. It would have to be a ודאי first day of his 14th year to be עוקר the חזקה of him not having שתי שערות.
    – HaLeiVi
    Commented May 26, 2015 at 23:06
  • You might have thought this is a theoretical question but it actually was very relevant to us this Hanuka. I had to travel on the first night and my older son was becoming bar mitzva that night. So he lit for the whole family, his first real mitzva and we waited until tzeit hakochavim.
    – mbloch
    Commented Dec 28, 2015 at 20:25

1 Answer 1


This is a matter of dispute among the acharonim. For example, in Shulchan Aruch O.C. 53:10, R. Moses Isserles writes that someone who will turn 13 on Shabbat should not lead the Friday night services because at that point he is not yet 13:

ובמקומות שלא נהגו כן אין לקטן לעבור לפני התיבה אפילו בתפלת ערבית אפילו הגיע לכלל י"ג שנים ביום השבת אין להתפלל ערבית של שבת דהרי עדיין אין לו י"ג שנה

Commenting on this, R. Abraham Gombiner explains that this is because we pray before night actually begins, thus the kid is still a minor. But if we would pray after it is already actually night then the kid can lead the services:

פי' דבמדינתנו מתפללין ערבית מבע"י והוא לא נכנס בשנת י"ד עד תחילת ליל שבת שהוא יום שנולד בו אבל אם מתפללים ערבית בלילה מותר לעבור לפני התיבה

According to this, the Bar Mitzvah takes effect the moment the kid's birthday begins, i.e. when the previous night begins. However, R. Naftali Tzvi Yehuda Berlin disagrees with this. In his commentary to Berachot 2a he cites the Talmud's question as a refutation of R. Abraham Gombiner's view. The Talmud asks why the Mishnah first discusses the time for the nighttime recitation of Shema and then discusses the time for the daytime recitation of Shema; it should discuss the daytime Shema first. But, says R. Berlin, if R. Gombiner is correct then this question makes no sense. Of course the Mishnah would discuss the nighttime Shema first because that obligation occurs before the obligation of the daytime Shema, since every person becomes 13 at night. From the fact that the Talmud asks this question, then, we can infer that the Bar Mitzvah does not take effect when night begins; rather, it goes by the time that the person was born:

מכאן יש ראיה להפוסקים דשני גדלות תליא משעה לשעה ודלא כהמג"א וסייעתו בסי' נ"ג ס"ק י"ג דתליא בריש מעל"ע דאם כן מאי מקשה הא סדר החיוב כך הוא תחילה של ערבית ואח"כ של שחרית אלא מוכח דבתר שעה אזלינן והדברים עתיקים

  • While interesting, it seems likely the OP was asking according to the MA opinion and just wondering how that is calculated practically.
    – Double AA
    Commented Feb 12, 2019 at 13:37
  • @DoubleAA You mean he just wants to know at what point the next day begins?
    – Alex
    Commented Feb 12, 2019 at 13:48
  • That's what I thought above in my comment. I'm also a bit confused. Perhaps we can say better when we can assume for these purposes the next date has begun. There are different kinds of Tzes etc. and it isn't 100% obvious a priori anyway that the beginning of night for nighttime Mitzvot is the same as the beginning of the next calendar day.
    – Double AA
    Commented Feb 12, 2019 at 13:55
  • @DoubleAA I agree with that comment, then.
    – Alex
    Commented Feb 12, 2019 at 13:57
  • @DoubleAA Judging by his follow-up question you're probably right.
    – Alex
    Commented Feb 12, 2019 at 14:20

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