A person gets up from Shiva (and ends Shloshim) on the morning of that particular day because of the principal of miktzas hayom kekulo, that part of the day counts as the entire day. Why does this not then allow shiva (or shloshim) to end after ma'ariv, the previous evening, which actually begins the final day?

According to halachipedia,

However, we do not apply this concept to keeping aveilus at night, and instead the mourners have visitors come in the morning and end aveilus when they leave. (note 18)

18 -- This is the practice as described by the Gemara Moed Kattan 21b. Tosfos there (s.v. “Afilu”) believe that the nighttime cannot count as a partial day, but Ramban (Toras HaAdam p. 215) disagrees. Maharam of Rothenberg, quoted in the Rosh (Moed Kattan 3:30) and paskened by Shulchan Aruch (Y.D. 395:1) held that the concept of מקצת היום ככולו can be applied to the nighttime in principle, and is therefore relevant for the thirty days of aveilus, but nighttime does not suffice for ending the seven days because of a need to have a seven day count, similar to the count of a niddah.

The Tosfos referred to on M"K 21b reads

י"ל מקצת היום ככולו לא הוי בלילה לענין שום דבר כדאמרינן במגילה בפ"ב (דף כ.) דשימור לילה לאו שימור הוא לענין שבעה נקיים:

This seems to be saying that the rule of the partial day counting for the whole doesn't include the evening regarding "shoom davar" which I see as an absolute exclusion and his evidence is that in Megilla, 20a, the counting of 7 clean days for the menstruant must include the morning of the seventh day:

MISHNA: One may not read the Megilla, nor perform a circumcision, nor immerse himself in a ritual bath, nor sprinkle water of purification to purify people and objects that had contracted ritual impurity through contact with a corpse until after sunrise.

The gemara there gives a specific list, and then goes through each of the examples given in the mishna and shows a textual source why the "day time" is a necessary component (even though, for example, the 7th day for a niddah begins in the evening). Why would that principle of day-time then be applied to any other unlisted (and not-textually supported) case?

I don't understand why computing the 7 days of shiva (or the 30 of shloshim) is inherently tied to the methodology of counting for a niddah or where that connection is codified.

The Shulchan Aruch's position is here and one should look at note #2 (it begs other questions about the categories it suggests).

  • Based on this logic, why sit shivah at all? מקצתו ככולו - just sit for an hour and it’s like the full week.
    – DonielF
    Commented Jul 4, 2018 at 15:22
  • 1
    @DonielF As far as I can tell, the principle is "hayom."
    – rosends
    Commented Jul 4, 2018 at 15:47
  • ר״ה י: - יום אחד בשנה חשוב שנה
    – DonielF
    Commented Jul 4, 2018 at 15:48
  • I don't understand your question. When it says שום דבר, it implies an absolute, including shiva. What else are you seeking that isn't answered by this statement?
    – DanF
    Commented Jul 4, 2018 at 19:07
  • @DanF The absolute is claimed to be derived from a mishna which lists 4 examples, each of which has a pasuk to justify its inclusion. The leap to "anything" doesn't make sense - if it meant "anything" in the mishna, why not say so?
    – rosends
    Commented Jul 4, 2018 at 23:32

1 Answer 1


The Aruch Hashulchan in (YD 365:2) יורה דעה סימן שצה סעיף ב writes:

ולכאורה כיון דמקצת היום ככולו, אם כן גם מקצת לילה די לענין שלושים. שכאשר עבר מקצת ליל השייך ליום שלושים – בטלה ממנו גזירת שלושים. דבשלמא בשבעה אי אפשר להיות כן, דבעינן שיעמדו המנחמין מאצלו (כב א) וכמו שכתבתי בסימן שע"ה, והמנחמים באים ביום ולא בלילה. אבל לעניין שלושים למה לא תחשב מקצת לילה כמקצת?

ובאמת כן דעת הרמב"ן והרא"ש בשם הר"ם (עיין בית יוסף). אבל דעת הרשב"ם והריב"ם דבלילה אין הדבר ניכר, ובעינן מקצת היום (עיין שם). ולא משום דמעיקר הדין כן הוא, אלא דכן מנהג העולם. וכן סתמו רבותינו בעלי השולחן ערוך. ומצינו בשומרת יום כנגד יום דשימור דלילה לא הוי שימור.

Translation of relevant bolded parts:

By The end of shivah we do not say miktzas hayom kekulo in the evening (preceding the seventh day) because the shivah ends when the menachmim (consolers) [of the seventh day] stand up from consoling the avel (as is stated in siman 395. And since mourners generally come both during the day and at night. (So with shloshim we would say miktzas hayom kekulo from the night preceding the 30th day.

This is actually the opinion of the Ramban & rosh in the name of the Rambam, but The Rashbam and the Rivam opine that (miktzas Hayom) in the evening it is not noticable, and therefore we require miktzas of the day. This is not main the Halacha but rather the minhag haolam (generally accepted custom). And it is the ruling of the Shulchan Aruch. And we find that [by shomeres yom...] שימור לילה לאו שימור הוא.

I understand this to mean that just as we see that שימור לילה לאו שימור הוא, and the Aruch Hashulchnan is assuming the reason to be as stated that the night shimur is not noticeable, so too by aveilus the evening will not sugffice for miktzas hayom since it is not noticeable enough.

  • what is the reference to "shomeres yom" and why would it be analogous (and therefore transplantable) to sh'loshim? Is the language of "shomer" used by sh'loshim also?
    – rosends
    Commented Jul 5, 2018 at 10:40
  • @rosends it has to do with Niddah. As I said it is an example of a place where we see that using the night for miktzas hayom is not noticeable. this is the reasoning that the Aruch hashulchan is basic on for all places to require miktzas YOM and not miktzas leila. Commented Jul 5, 2018 at 13:07
  • So then the mishna needed only give the example of Niddah and generalized it to every case. But it didn't. It gave 4, including niddah, and supported each with a posuk. Why connect any of them to anything outside that group? BTW, in your translation, you write "And since mourners generally come both during the day and at night. " If that is accurate, then miktzas hayom should count for shiva. This comports with the following transition "aval l'inyan shloshim" BUT for the concept of shloshim, why don't we think the miktzas of the night is a miktzas. So I'm a but confused.
    – rosends
    Commented Jul 5, 2018 at 17:43

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