If Tisha Ba'av fell out on Shabbos, and therefore it was pushed off to Sunday. Is a Bar Mitzvah Boy obligated to fast if he turned 13 on Shabbos? In other words: Does the fact that Tisha Ba'av fell out on Shabbos and now moved to Sunday constitute the Boy obligated in the fast or not? Please source.

  • 2
    Do you mean that he turned 13 on Sunday?
    – mroll
    Commented Feb 28, 2019 at 6:41
  • As I see it, if he turned 13 on Shabbat, then he would need to fast because on Shabbat he was liable to fast. A question would arise if he turned 13 (ie 13 and a day counting a part of a day as a day) on Sunday (Motzei Shabbat). Then on Shabbat he would not have needed to fast, but the fast was deferred until Sunday, when he achieved bar mitzvah and with it the requirement to fast.
    – Epicentre
    Commented Mar 1, 2019 at 15:54

1 Answer 1


The Kovetz Halachos writes that he should fast if possible. He brings the opnions on page 21: footnote 17. The Avnei Nezer 426 was muspak about this ,and explains whether it's considered a tashlmin or not . He seems to come out that it is and a katan would be patur. The Maharsham 3:363 also seems to be maikel, however there still may be an Inyun by chinuch when it comes to tisha bav. The Divrei Malkeil 5:130 argues on the Maharsham and holds that a katan is chayav to fast since its not considered a tashlumin. Rav Asher Weiss also held that it's not considered a tashlumin, but rather it was instituted by Chazal to be pushed off ,so one would be chayav.

  • The fact that no one discussed this before the 19th century supports those who claim he's the same as any other adult
    – Double AA
    Commented Feb 28, 2019 at 14:39
  • Sounds about right
    – sam
    Commented Feb 28, 2019 at 14:59
  • @DoubleAA, all it supports is that the answer was obvious. Not what the answer was.
    – msh210
    Commented Feb 28, 2019 at 16:41
  • @msh not only obvious but obvious from the available texts none of which mention an exception to the rule that adults fast. I can edit to clarify that enthymeme
    – Double AA
    Commented Feb 28, 2019 at 16:45

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